My worst loss was not nearly as bad as some of your stories, but perhaps it was the context:
I tend to work long hours on my music, and it is not uncommon to pull 12-15 hour sessions on score prep/production. One evening I made what I still consider to be one of my own fave tunes- to this day. After 12 hours of solid progress, resulting in a bouncy house tune, mixed JUST so, arranged JUST so. The parts melded perfectly into the limiter, the final product somehow resembled my favorite old school artists- warmth punch, raw and wrong and ready to just enjoy. I was so, so, so excited to have made a track in a night that I felt proud of, especially back when I only had a couple tunes finished.
The next morning, I opened up the project file to show my now fiance.
“would you like to restore your crashed session?”
“hm… I don’t remember ableton crashing last night… and it was only hours ago!” yes, restore
The project was blank, the whole arrangement and all its glory, just vanished, gone into the ether. The thing is… the next thing I did was… I accidentally pressed command-S instead of command-Z… Saving the blank slate… !!!
Turns out, the night before, I accidentally highlighted my arrangement (which should be a disable-able or multi-step function IMO) and pressed delete (accidentally of course) just as I was quitting, or just before. This crashed my Live, and upon opening it the next morning, offered me the option to undo the damage.
Saving it destroyed the undo steps. I’ve always wondered about that moment, when I had a chance to save that project that got away. Still haven’t quite gotten over it…
So, the rush of the writing process, the lull of deep, well deserved sleep, and the crash and burn upon discovering the horrible truth! I got one bounce of it, and have since moved to saving the progress of songs with appended numbers, to be safe… I couldn’t touch my computer for a week.
tldr: Made a project, accidentally saved a deleted arrangement over it, died a little inside.