We’ve all done it before: you click the delete button, but didn’t really mean to get rid of that photo album or document forever! You search frantically through the Recycle Bin for any traces, but alas, the treasured file you accidentally banished is gone from your hard drive forever…or is it?

With the help of data recovery software, you can undo the mistakes of the past, and even unearth long-forgotten parts of your storage media that you may not know existed in the first place.

But what exactly is data recovery software, and how does the whole process work? How can it bring files back from the dead after they’ve supposedly been forgotten? And maybe most important of all: is it going to cost you anything?

Read on in Comparitech’s guide to find out everything you need to know about how data recovery software works, as well as a few recommendations on which companies we think provide the best free software options on shelves in 2017.

How file storage works

To start on our journey down the rabbit hole of how data recovery software works, it helps to explain how a file actually gets on a storage device to begin with. Many different types of storage media are in use throughout the world, and some of the most common places people keep their files will include:

  • Hard drives (desktops, laptops, external HDDs)
  • Solid-state drives (desktops, laptops, external SSDs)
  • Flash drives (USB thumbsticks, tablet/smartphone memory)
    CD/DVDs (disc-based memory)
  • SD cards (smartphone expansion slot, camera memory)

Though you still might find the occasional luddite out there who’s determined to make floppies a “thing” again, other than those fringe cases the majority of any data you find stored today in the consumer space will live on one of those six types of memory storage.

We could break things down even further and dive into the nitty gritty details of how each storage medium has its own set of filesystem substructures (NTFS, FAT32, etc), but we’ll leave that lengthy explanation for another day.

On the subject of recovering data after it’s been deleted, all you need to know is that when you download a file, click on a link, or even just turn your computer on from sleep – data is being written and rewritten thousands of times per second to your storage media in the form of encoded binary.

Whether it’s a funny cat video or an important PowerPoint presentation, ultimately any type of media that’s been stored on a digital device will boil down to a series of 1s and 0s. Think of the disk in your hard drive like a vinyl record: when the wax is set it’s able to reproduce the frequencies of your favorite song; but it needs a record player to translate the peaks and valleys of the original recording into something the receiver can read as audible music.

A hard drive or CD-DVD drive works in much the same way, writing data to a disk which has billions of peaks and valleys etched into the surface. How the patterns get written on the disk will vary depending on the storage medium – classical hard drives rely on magnetism, for example – but for every valley the computer knows to assign a zero, and every peak gets a one.

magnetic imaging hdd

The needle on the hard drive (or laser of the CD-DVD reader) reads those 1s and 0s (otherwise known as “bits”) thousands of times per second, and displays that digital information to us with the help of other components like the CPU, RAM, and GPU.

Of course the true technical explanation of this process is far more complicated than anything we could fit in a standard article, and that’s not even counting what we encounter once we move into the realm of flash-based memory chips. All this in mind, the core idea still remains the same at its most basic (nerd-pun not intended).

So now that you know how the data gets onto the drive, where does it all end up once you decide it’s time to take out the trash?

How file deletion happens

Well…it’s complicated.

Firstly, we should mention that if you haven’t already, head on over to our companion article How to securely erase your hard drive, SSD, or mobile phone, which gives a detailed breakdown of exactly how a device gets rid of unwanted data and where it really goes after you’ve said your goodbyes.

The abridged version goes something like this: even though you just can’t get enough of Grandma’s RE:re:RE email chain attachments that come with the picture of the dog wearing bunny ears (third one this month), eventually everyone hits a point where they run out of available space on their main storage drive, and they need to sort through their Downloads folder for a little light housekeeping.

But how does deleting a file from a drive actually work, and once the deletion is done are all traces of the file really gone for good? If deleting something is so easy, why does data recovery software exist in the first place?

As an example, we’ll use Windows 10 to explain the different ways that an operating system can handle a “delete” command when it finally comes time to bring down the axe on your “Dogs Wearing Different Animal Ears” folder full of Grandma’s emails.

Soft delete

The first would be what we’ll call a “soft” delete, which is less of a deletion and more of a reallocation, in a sense. Instead of actually writing over the data in a sector in a such a way that more, new data could theoretically be stored in its place, a soft delete will simply move files from the original folder in your hard drive to the Windows Recycle Bin, which still lives on your hard drive.

This means your “deleted” files could stay for eternity in the Recycle Bin, continuing to take up the same amount of space as they did before. It also means that anyone with access to your account on that computer would be able to see what you tried to delete unless you emptied it.

Permanent deletion

After you empty your Recycle Bin (or Shift+Delete an individual file with the keyboard), the second type of deletion you’ll get in Windows is the so-called “permanent delete”, which you may recognize from such warning prompts as the one seen below:

permanent delete

This is where things start to get a little mucky.

See, when a file gets “permanently” deleted, the binary bits of the sector where that file was stored aren’t so much being overwritten as they are being de-listed from the proverbial phonebook. The drive tells Windows that the sector which was previously a “1” is now a “0”. This doesn’t mean the data that was there before has been overwritten yet, just that it could be if the operating system needed to make room for new files.

The reason you can’t see the data anymore is because “deleting” a file through Windows only removes traces of it from what’s known as the “Master File Table”, a sort of guide that acts like a recipe book to tell your device where it can find all the pieces of a file and instructions on how they’re supposed to fit together.

In the case of NTFS-formatted drives, all the bits and bytes of a file aren’t stored in perfect unison, but rather in more of a jumbled mess that’s scattered throughout various parts of the drive. When you “permanently” delete a file through the Recycle Bin, you’re actually just erasing the reference point that the Master File Table uses to bring that data together into a cohesive whole. The MFT then registers the previously occupied space as free, allowing the device to overwrite that section as necessary.

If you’re still a bit lost, it’s easier to think of it like this: let’s say you send a document with valuable information through the shredder. You then take that shredded document and put it in the trash without a second thought, because even though each strip may have sensitive numbers on them, without the context of the original document to refer back to none of the individual strips will make sense on their own…right?

As it turns out, not so much. Even though it seems like it would be too labor intensive for someone to go through the trash and try and glue every strip of the document back together by hand, data recovery software suites are designed to do exactly that when digging through your “deleted” digital files.

So if soft deletes don’t free up space and permanent deletes don’t actually get rid of the data you’re trying to get rid of, what other options are there?

Formatting

The last way a file can be deleted off a drive is if that drive is formatted, which happens in one of two ways: quick format, and full format.

We’ve already covered the differences between these two drive cleaning commands in a previous article, but what’s important here is how they can each still leave traces of your old data on a drive even after all the sectors have supposedly been written back to zero.

A full format is the easiest and most accessible way for the average user to make sure that data on their hard drive is just about gone for good. But if a data recovery operation is run on that hard drive within a reasonable amount of time, there still might be a chance that the file fragments from the previous build would be fresh enough to get Humpty Dumpty put back together again.

How data recovery software works

Now that we’ve talked up all the different ways that data can get “deleted”, how exactly does data recovery software resurrect buried files from the grave?

Moving right past a whole tome of technical jargon, at its most layman data recovery software works to restore lost, deleted, and sometimes even corrupted data by deeply scanning a drive for any files recently marked as “deleted” in the drive’s master boot record.

The boot record is where a drive will decide what sectors appear as a “0”, and which appear as a “1”. The software will carefully sort through any results that have a 0 attached, and then do a dive to hunt for any scraps of files that carry that same marker.

data recovery deletion

There are a number of inventive methods that data recovery software can use to stitch any scraps found during the deep scan back together. These can range from searching through titles and metatags to find similarly tagged data clumps, to using new versions of a file already on the drive and patching pieces of those back into the deleted file to make it whole again.

No matter how Frankensteinian the techniques might get, hopefully the end result of what comes out on the other side is a complete picture of the deleted file, ready to be restored from the destroyed wreckage that used to be your Recycle Bin.

It’s not common that data recovery software can retain exact filenames for deleted data, or even the original date when a file was modified. But, what it lacks in metadata recovery it can usually more than make up for when it comes to getting the complete file ready for use again after it was supposedly dead and gone.

Features to look for in data recovery software

When deciding which data recovery software will be the right pick for your own needs, there are a number of different factors that should be considered before making the final choice.

  • Operating System Compatibility: While it may seem obvious to some, the first feature to look for is whether or not the data recovery software you’re using actually supports the operating system you’re trying to recover files from. There are many recovery suites which have PC versions, a few with Mac compatibility, and just a few more made to cover options like Linux specifically.
  • User Interface: Data recovery is an extremely delicate process, and one wrong move can mean the difference between bringing a file back from the brink and losing it to a black hole forever. This is why it’s vital that the UI of your preferred software is clean, easy to read, and has plenty of double-checks in place that might prevent more novice users from doing permanent damage the next time they try to un-delete something.
  • File Types: If you know the specific file you’re trying to find after a deletion, be sure that any data recovery software you go with is capable of scanning/recovering that filetype first. Not all data recovery software is made equal, and while many are capable of recovering basic files like text and pictures, others can go as far as recovering lost emails or even full videos, as long as they weren’t lost too long ago.
  • Supported Filesystems: We talked briefly earlier about the different ways that hard drives can organize the files stored on them, whether it’s through NTFS, FAT32, or any one of the 10 or so other variants. As is the case with file types, you’ll want to check the feature list of your data recovery choice and make sure it matches up with the drive you’re trying to scan.
  • File Preview: This is a feature that’s unique to only a few data recovery software suites (Stellar Phoenix does it best), but it can be a very helpful tool that lets you see the file you’re trying to recover before it actually comes back. This means that if you’re trying to find a specific photo, but all the other identifying information has been lost (filename, metatag, etc), you can simply flip through the previewed images until you land on the one you were looking for.
  • File Shredder: This isn’t a hard requirement in my book, but it’s still a nice bonus add-on to grab if you can get it. File shredders included with data recovery software are often the best and most secure way to delete a file for good, guaranteeing that no one will be able to find it after the secure deletion process completes.

I accidentally deleted an important file, what’s next?

If you delete a file on accident, your best bet to getting it back with the least amount of corruption is to stop using your computer for anything else except to download one of the data recovery software programs featured in our list below.

This is because even though bits of the deleted data are still floating around the drive, the more you use the drive, the more of a risk there is that the original sector will be overwritten with another pass of binary, making it harder to figure out what it was supposed to look like in the first place.

If we go back to the shredded paper explanation, it would be as though your computer began dumping thousands of new strips of paper with new information on top of the original shredded document, but all in the exact same trash bin.

While technically the original strips are still hiding in the bin somewhere and they could in theory be put back together again, the longer you let your device add new strips to the pile, the harder it’s going to be for the software to find every strip it needs to recover what was lost.

To avoid this, we recommend disconnecting the drive completely while you get your data recovery software downloaded and installed. It may sound counterintuitive, but this will prevent your computer from accidentally rewriting data to any vulnerable sectors and give you the best chance of success once the data recovery process has started.

Best data recovery software for 2018

Data Rescue 5

data rescue 5

Data Rescue 5 may not have the prettiest user interface or the most intuitive configuration options, but what it lacks in aesthetics it more than makes up for in raw, unchecked results.

Data Rescue 5 ran some of the most intensive deep recovery scans we’ve tested this year, and aside from scoring 100% on every file we set out to find, DR5 even pulled out a few ancient files we thought had been long since dead and buried.

Add to that a huge number of supported filetypes and a ridiculously granular search mechanism that can both save you time and wear on the drive being scanned, and you’ve got a winning combination in data recovery that will be difficult to top for a long time coming.

EaseUS

easeus data recovery

EaseUS also impressed us with its deep scanning abilities, turning in a respectable number of results that only just barely missed the 100% mark due to some corrupted file previews. Aside from that small hiccup, EaseUS offered a solid user experience, a 30-day trial, and one of the largest number of customer support options in the business.

EaseUS also happens to be one of the cheaper options here at just $69.95 for a lifetime Pro license, where other software may cost upwards of twice as much and might only return less than half the results we achieved during our time with EaseUS.

Remo Recover

remo recover data recovery

Remo Recover may bring back some bad memories for Windows 8.1 users upon first glance at its interface, but underneath the hood is a powerful, user-friendly data recovery application that gets most of the job done with only a single scan.

With an imposingly impressive number of features, scan options, and lightning-fast returns, there’s a lot of reasons to like what the guys at Remo Recover are up to. The only drawback we can think of here (besides the triggering Metro tiles) is Remo was a bit of RAM hog while the scan was in process, but aside from those two admittedly minor complaints Remo Recover is a great choice for Windows and Mac users alike.

Stellar Windows Recovery

stellar windows recovery

Stellar Windows Recovery makes it easy for users to get their first scan up and running in minutes, and should be the first choice for any novice users who might be newer to the world of data recovery.

Stellar Windows Recovery would have taken a higher spot if the metrics were based on user-friendliness alone, but it did return some mixed results during testing that might not make it the best choice for more serious recovery jobs caused by deeper deletion tactics.

Disk Drill

disk drill windows recovery

Finally we come to Disk Drill – which despite its speedy scans in most of our tests – seemed to struggle in other more obvious areas like UI, configuration options, and customer support.

Those complaints aside, Disk Drill is still a great program to consider if you’re low on time and want something that just works with a few clicks. Much of the process has been streamlined down to its essential parts only. This makes it a perfect pick for anyone who doesn’t want to spend a ton of time bogged down in the mess of setting new scan types, and just get their lost photos or files back as quickly (and hassle-free) as possible.

When data dies for good

hard drive broken

Even though data recovery software is a great option for people who may have recently deleted a folder or formatted a section of a drive, it bears mentioning there are a number of other data loss scenarios which can’t be fixed by any kind of software application, no matter how good it is.

These include logical failures of the drive (filesystems/firmware on the fritz), physical failures (mechanical parts malfunctioning, actual damage to the drive itself), or trying to recover files that have been deleted for so long they’ve essentially become unsalvageable past a certain point.

If you’ve been trying to recover data off a drive that’s making any sort of clicking, whirring, humming or chirping noises, stop running data recovery scans immediately and jump in Google Maps to check to see if there are any data recovery businesses in your area that can take a look at the situation in person.

Keep in mind ahead of time though that a visit to the local data recovery specialist visit could cost anywhere from a few hundred dollars up to several thousand, depending on the severity of the damage to the drive and the parts/labor needed to get it fixed.

professional data recovery

Only use an in-person data recovery service if you know for certain there’s no way of getting the data back that was lost via the software below, and you’re willing to put down a good chunk of cash just for a slim chance of seeing it alive again.

When data recovery fails

The reason we mention that there’s only a chance you’ll get back the data you’re looking for is because, ultimately, there are no guarantees in the world of data recovery. Many of the services mentioned above will get the job done if you’re trying to restore files that have been deleted in the past few days, but as time goes on with the computer running, their efficacy begins to drop off a cliff.

Make sure whenever you sign up for a new service to keep your expectations in check about what these programs can and can’t do. If you’re trying to find an old photo that was on a hard drive three years ago and gone through a couple of formats since, there’s not a software (or hardware) solution in the world that’s going to to be able to get it back for you.

broken hdd recovery

Similarly, if the hard drive has had more than a few write-zero passes administered by a secure deletion program, unless you have a military-grade recovery network by your side, you shouldn’t expect that data to come back in any recognizable format ever again.

That said, for anyone who has only recently deleted a file and are sure that they’re still in the window of opportunity to get it back, there are plenty of great free data recovery software options to get you rolling in the right direction!