Missing World

I had a single player world that I have put about 400 Minecraft days worth of time into and was in the middle of expanding my base in game when all of a sudden the game crashed. I logged back in and for some reason the world was missing, so I then tried to look in my files for one of my backups of the world to try that, and all my backup files for the world don't exist anymore. I don't know what to do and I was wondering if anyone else has experienced this and what to do about it if possible. I should also say that the world was originally loaded in during 1.16.1, and had been updated and backed up with new releases