Save files corrupted Sims 3

@dmacay95  Okay, so it probably is the .nhd file that's corrupted.  (Sometimes it's a different one, and the only way to find out is to test.)  You can try the reverse though—clean game folder, start a save in the same world, delete the new .nhd file, drop your old one in—to see if it helps.  If it does, save the game and make a backup.  It may be that your save will fail to load again soon, and in that case your options are to either pack up your families and drop them in a new save, or use mods to try to fix the world.  Both are more likely to work in this backup save than in the one you keep playing forward.

Besides, keeping backup saves is a good idea in general;—you never know when something will break.  I use "save as" to rename my saves at least once a sim-day; this creates a new save file rather than overwriting the old one.  I keep the last 4-6 copies and delete the older ones when I'm sure I don't need them.