Like I said: I'm an idiot.
My parents moved out of their house into an apartment, meaning I had to clear a metric shit ton of stuff accumulated over the years and throw it out. One of these things was a binder I used for various burnt discs, including backups made over the year. I took the most recent one of these, placed it in a spindle with some other disks and took it with me. I "tossed the rest out".
Fast forward a month or so and I'm also moving to a much smaller place (and throwing out a metric shit ton of stuff). In the downsizing fervor I combine my two spindles of disks - one for audio cds, one for data into one of just the disks I want. I throw out one copy of the disk. The rest of the spindle is literally the backup disk and a bunch of audio CDs.
While in my parent's storage locker I come across a the binder from before. I guess I never tossed it. "Great, I'll just leave this hear".
Unpacking my stuff I realize I no longer have a CD player at all and toss out the spindle of disks. Shortly after, I vaguely remember realizing that I had my backup on there. Not a big deal, I still have the "one in the binder", but I'll burn another backup anyways because it's about that time.
Working from home a couple of weeks later and I'm having some kind of computer problem. Might as well switch to the notebook and get paid to reformat, right? I copy "my documents" over to my non-os drive, along with other stuff, and reformat my main drive. Upon putting the data back I realize that the file structure changed between XP and Windows 7 - "My Pictures" is no longer a subfolder within "My Documents" but rather a separate folder with only a shortcut in My Documents." Pictures have been deleted.
Almost hilariously, it immediately hit me that I'm a moron and that the backup disk is no longer in that binder in my parents storage locker and I had actually thrown out both copies. Everything else was fine as it was copied over to the second drive. The only other thing that would have been affected is music but that was all kept on the second drive anyways and just linked through a shortcut in "My Music". Sure enough, there were actually no other backup disks in the binder (I had hoped I at least had one from years earlier). In the confusion from all the moving and everything I must have gone through the binder itself, pulling out and throwing out disks I didn't need, only deciding at the end to change plans and just take the 2-3 I wanted to keep and put them in a spindle.
Basically, I fucked up.