I updated a world of mine from 1.17 to 1.18 and the transition went fine. I played on the world for a few hours yesterday and today making a large amount of progress. However the game froze while I was in a jungle biome, as it consistently does, and wouldn't respond. I couldn't exit the world, the launcher or get task manager up to close it so I shut down my computer and rebooted. When I launched Minecraft and went to go back to my game, expecting some minor set back to the last save, I found the entire world had been deleted off the launcher.

The save file is still in my files on Windows Explorer and the old 1.17 save is there. I can access the old save and open it in the launcher however the current 1.18 save I have, had a extra files so I put them in the 1.17 file and then opened the launcher and the old backup world no longer exists on the game.

I expected a set back from force shutting down my computer but completely loosing the whole world and this problem with the files isn't normal and now I am back at square one of a brand new world