Missing File

I've been working on a piece for several years on MS3. I never got the chance to put it in MS4 because I literally cannot find the file anywhere on my computer. I have hidden files and encrypted files shown and still nothing. I've checked my recycle bin and everything, but I cannot find this file anywhere. It dissipated into thin air one day and I haven't seen it since. It's not in any of my msbackup folders either.