Why Are Some Deleted Files Not 100% Recoverable?

Are Files That Are Only Partially Recoverable of Any Use?

Photo of a missing jigsaw puzzle piece
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It's true that some of the files you try to undelete with file recovery software aren't completely recoverable but why that's the case is a bit complicated.

When your computer writes data to your hard drive, or some other storage media, it's not necessarily 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 all over the drive it's stored on.

As you may have learned elsewhere in my data recovery FAQ, 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 made up your deleted MP3 file still exists.

That was a simplistic example, but hopefully that helped you understand why certain percentages of some files still exist.

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, unfortunately, in most cases, no, restoring a file that has missing data will usually result in a worthless file.