If the number of questions I get about file recovery are any gauge of an article's popularity then my free file recovery software list must be one of the more popular pieces on my site.
In other words, the complicated and often misunderstood topic of recovering deleted files rightly generates a lot of confusion.
So to both shrink my ever-growing inbox, and to settle the minds of those that decide not to take the time to ask a question, here are answers to some of the more common questions I get regarding these "undelete" programs and file recovery in general.
"I just deleted a file that I want to get back. Am I out of luck since I don't already have a file recovery program?"
No, not having a file recovery program already installed doesn't preclude you from being able to recover a file. Having a file recovery program installed doesn't mean that it's watching for deleted files or anything like that.
So if you've deleted a file you want back, go download a file recovery program, and run it. Assuming that space hasn't already been overwritten (see the next question below), you'll probably have no problem undeleting the file.
Unless you mean quite literally that you just deleted a file? If so, check the Recycle Bin. It's probably there since that's what it's for. See How To Restore Deleted Files From the Recycle Bin if you've never restored a file from the Recycle Bin.
"Will a file recovery program undelete anything I've ever deleted?"
The short answer is no, but it's a bit more complicated than that.
While this might surprise you to learn, the information in a file, for example, doesn't actually get removed when it is deleted. The file system, which is like an index that keeps track of where the pieces of a file are located, simply marks the areas that contained the file as free space that the operating system can overwrite with new data.
In other words, the map that held the location of the file is removed from the index, essentially making the file invisible to the operating system... and you.
So a file recovery program works by exploiting the fact that, while the directions to a file are missing, the actual file is not, so long as that physical space has not been overwritten by something new already.
Now that you know a bit more about how it works, I can better answer the question: a file recovery program isn't likely to undelete everything you've ever deleted because at least some of the physical space occupied by those deleted files has likely been overwritten with new files.
"How long is too long before a file I've deleted becomes unrecoverable?"
Technically, it's not a "how long" question so much as it's a "how much data have you written to the media since deleting the file" question.
As I discussed in the answer to the previous question, when you delete a file, you don't really remove the data, only the directions to it. The space occupied by that data is marked as free and will eventually be overwritten. The key, then, is to minimize the writing of data to the drive that contains the deleted file.
In other words, the less writing activity (saving files, installing software, etc.) on the drive, the longer, in general, a particular file will be able to be recovered.
For example, if you delete a saved video and then promptly turn off your computer and leave it off for three years, you could theoretically turn the computer back on, run a file recovery program, and restore that file. This is because very little data has had a chance to have been written to the drive, potentially overwriting the video.
In a more realistic example, let's say you delete a saved video. For weeks, or even just days, you use your computer normally, downloading more videos, editing some photos, etc. Depending on things like how big the drive you're working from is, the amount of data you're writing to the drive, and how big the video you deleted is, chances are it won't be recoverable.
"Do any of these programs undelete files that I've deleted from my flash drive/SSD/external hard drive/media card/iPod/CD/DVD/BD?"
Yes, many do. Whether a program supports one storage device over another depends on the file system that the particular file recovery program supports.
Most file recovery programs support any device that you can plug into your computer and display the contents of as a drive.
"What if I delete a file from a network/shared drive? Can a file recovery program undelete those?"
No, not exactly. The reasons why are a bit complicated but basically it's because your computer doesn't actually "control" the drive, another computer does.
However, if you have access to the computer that the shared drive is actually located on, go there and try to undelete the file with a file recovery program.
Unfortunately, this also applies to network storage devices you might have on your network that are not directly connected to another computer. While it might seem strange to think about, there is actually an operating system supporting that drive and file recovery would have to be initiated from within that drive. A Windows or Mac based file recovery program won't be of help there but you should log on to the web-based administration for the device and see if there are any integrated file recovery features that might be helpful.
"I found a file recovery program that looks good but there are two download options: 'portable' and 'installable.' Which one should I use?"
They are identical programs. The difference is that one installs to your hard drive, the other runs self-contained.
In general, I like portable, self-contained programs. They don't leave shortcuts, DLL files, and registry keys all over your computer. That just "feels" better to me.
Now, multiply that "like" times one million and that comes close to how much I prefer portable file recovery programs over installable ones, and here's why:
If you've been reading through all the questions in this FAQ, then you already know that the single most important thing you can do to make sure a file you've deleted will be recoverable is to stop writing information to your hard drive. If you didn't know that, now you do.
Installing software is one of the most write-heavy things you could possibly do, so" installing" a file recovery program is a very ironic, and potentially destructive, thing to do.
In a perfect scenario, which may or may not be possible for you, you'll choose the portable version of a free file recovery program, download it to another drive, and run it directly from there. Where you run it from doesn't impact where you search for deleted files on, so don't worry about that.
"The file recovery program I'm using finds a lot of files but few of them are 100% recoverable. Why are only parts of my deleted files available for recovery? Will I still be able to open these files if I recover them?"
When your computer writes data to your hard drive, or flash drive, or whatever storage media, it's not written to the drive in a perfect order. Divisible pieces of the file are written to parts of the media that may not sit next to each other physically. This is called fragmentation.
Even files we might consider to be small contain many thousands of divisible pieces. For example, a music file could in reality be heavily fragmented, spread over different parts of a hard drive.
As you may have learned several answers above, your computer sees the area occupied by a deleted file as free space, allowing other data to be written there. So, for example, if the area occupied by 10% of your MP3 file has been overwritten by part of a program you installed or a new video you downloaded, then only 90% of the data that comprises your deleted MP3 file will still be available for restore.
That was a simplistic example, but hopefully you get the idea.
To the question of the usability of just part of a file: it depends on what kind of file we're talking about and also what parts of the file are missing, the later of which you can't be sure of. So in most cases, no, restoring a file that has missing data will usually result in a worthless file.
"My computer won't start at all but I need to get my files off. Can a file recovery program help with that?"
No, a file recovery program isn't going to help get your computer started. Keep in mind, just because your computer won't start, doesn't mean your files are gone; it just means that you can't access them right now.
What you need to do is get your computer started again. See How To Troubleshoot a Computer That Won't Turn On for help with that.
"I have determined/was told that my hard drive is completely dead/broken. Is there any chance that one of these file recovery programs will be able to get my important data off of it?"
If by dead or broken you mean a physical problem with the hard drive, then no, a file recovery program isn't likely to help. Since file recovery software needs access to your hard drive like any other program, it is only valuable if the hard drive is in otherwise working order.
Physical damage to a hard drive, or other storage device, doesn't mean all hope is lost, it just means that a file recovery tool isn't your next step. Your best solution to recover data from a damaged hard drive is to employ the services of a data recovery service. These services have the hardware, expertise, and lab environments necessary to help repair and restore the data from damaged hard drives.
However, if you're experiencing a BSOD or some other major error or situation that's simply preventing Windows from starting, that doesn't necessarily mean that your hard drive has a physical or unrecoverable problem. See the answer to the last question for more on that.