Re: sim disappeared and game glitch
@sberyy_cat Hi! I'm very glad you were able to get your save back. There are a few things I wanted to mention here. As @SimmerStar4 was suggesting, it's a good idea to regularly create backups for your saves if you're worried about losing anything. You can get the save location for any save from the Load Game screen.
Use this to identify the file path, then go to your TS4 saves folder, copy the actual save file (you may want to copy all versions), and paste it into another folder either on your PC / Mac or onto a thumb drive. Then if you encounter a problem and can't recover an in-game save, you can copy that saved file back into your TS4 saves.
Something else that @SimmerStar4 mentioned that is also important ... You want to make sure your mods / CC are updated to the latest version of the game.
Lastly, while using the WW mod in particular, you should only save your game when you are in Live Mode or Build Mode. Saving the game from Worlds View may cause some issues with the game. This is related to an update a while back that changed how the game saves. It could impact other mods as well. Happy Simming!