Q: I accidentally deleted some files. I heard it is possible to recover deleted files. Can I get my files back?

– submitted by Ryan O’Day, Wang Gang Asian Eats

A: This question is quite common and now that I think about it, I’m surprised I’ve never covered this topic before. Usually this question is asked in two different contexts. The first is in the context of data security. People want to know if data they’ve deleted could be retrieved by someone later. The second context is what what prompted this question. Someone accidentally deletes a file and wants to know if they can get the file back. The answer to this question depends on two main factors.

The first factor depends on how the file was deleted. Most files when they are deleted from a computer, aren’t so much wiped from the hard drive (imagine erasing a blackboard) as they are simply “forgotten” (imagine losing a treasure map). The data is still there, but the computer simply doesn’t know how to find it. Note that many computers now have a “secure erase” function where it actually does wipe the data from the storage device. In this case, a securely erased file is virtually impossible to recover. Also certain “files” such as e-mail messages are actually stored inside a database file and it can be extremely difficult to recover those types of deletions.

The second factor is the time passed and/or the usage of the computer. Basically, once a computer forgets about a file, the area where the file was stored is now available to be reused for future data. How quickly this area on the storage device is reused determines how likely the data is to be recovered. Once deleted data is overwritten, recovery of the data is all but impossible except for the most specialized (and expensive) data recovery companies. Generally speaking, the sooner you attempt to undelete a file, the more likely you are to be successful. Basically, if you stop using the computer, then you reduce the possibility that the computer will overwrite your deleted data. But it is possible for a deleted file to be overwritten almost immediately, so there’s never a guarantee that deleted data can be recovered.

Of course, an ounce of prevention is worth a pound of cure and it bears repeating once again – back up your data! If you have a backup, you do not need to worry about undeleting a file. But of course you’re reading this article for a friend, right? So in the case that a “friend” accidentally deletes a file, what should they do? Make sure to tell your “friend” to immediately stop using the computer and shut it off. Ideally, they should then call a computer professional who is knowledgeable about recovering deleted files. Tell them not to call their nephew who is a “computer genius”.  This is really a job for a competent professional. There are software programs that can scan a drive for and recover deleted data, but in the wrong hands, your “friend’s” deleted data could be overwritten.

If you have a technology question, feel free to submit it to me and it may be featured in a future article