Again and again, we are reminded by computer gurus to be sure to backup anything on our computers that we don't want to lose.
Still, you'd be amazed at how many users, both personal and professional, don't bother to do so. I once had a nightmare scenario play out in a radio facility where the main server died and a good chunk of the recorded audio music, commercials and all just went poof in a matter of seconds. I had only been on the job a short time and when I asked where the backups were all I got was blank stares. It seems the former Operations Manager had simply not bothered with backups at all. There were none. It took months to recover from that crash, when a good backup plan would have made it possible to restore everything in just a few hours. Ever since then, I have been obsessive about backups.