Reset worlds to original files (help!)

You will have to re-download them, I'm afraid. Whenever I try out fixed worlds, I rename the original world, like x.world -> x.old , and I will leave both versions in place. If I want to go back to the old file, I first rename the new world file to x.new, then x.old -> x.world .

Keep in mind that you cannot swap world files for existing saves, as the street and lot positions are stored in your save file, only the terrain comes from the world file. You will get ugly mismatches if you do that. That's one reason to always keep the original files, because you may want to go back to an old save that uses the other world file, and you can just switch them out by renaming them.

Tank you @Turjan . I ended up reinstalling the whole game. I really have to start making backups...
Btw after i reinstalled the game i followed the "sims 3 steam performance guide" and changed some things in some files, all those things... but there was a step that was to open the nvidia control panel to recognize the game, but my control panel opens and closes immediatelly and i couldn't do that step. I googled the problem and tried to fix it but nothing helped... then i decided to open the "geforce experience" app (i think it's called something like that). That app automatically optimized the game, or so it said... i can notice graphics are better and they recommended playing fullscreen, which i didn't do before... but i'm not sure if this app does the job well done or if i will have problems later...