I had online backup of the written part. It was 12+ years ago so even that wasn't that common. But the main project was a composition, score + electroacoustic piece. (music master’s). At some point, I made a backup save on an external drive and forgot to change back the save location to my internal drive. One day I was using the vacuum cleaner, the hard disk power cable got caught in the vacuum cleaner and fell out. The external drive was broken, and I realized I had been making all of my saves on it. I’ve lost months of work, had to start over the piece, and I wasn’t able to submit my piece and thesis until the following semester. Now I teach computer music and I always tell that story to my students lol.