Will a Data Recovery Program Undelete Anything Ever Deleted?

Are All of My Previously Deleted Files Available for Recovery?

Picture of stacks of folders reaching into the sky
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The short answer is no, a data recovery program will not "undelete" anything, 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 coordinates that held the location of the file is removed from the index, essentially making the file invisible to the operating system... and to you.

Of course invisible is very different than gone forever, which is great news.

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.

So now that you know a bit more about how it works, I can better answer the question: a file recovery program is not 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.

See How Long is Too Long Before a File I've Deleted Becomes Unrecoverable? for more on how long it tends to take for files to be physically overwritten, whats sorts of files tend to be overwritten sooner than others, and a lot more on this somewhat confusing topic.