Decide if you want to restore the latest game you've been playing, or if you want to go back by a few days.
Never alter game files while the game is running. If you see that your game is corrupted as of the latest load, you can easily revert to any older version of that same save point, potentially losing no more than a few Sim hours of progress. The higher the version number, the older the file (.ver4 is the oldest save point within the series). save file extension is the primary version of that save point. Find your save files at Documents > Electronic Arts > Sims 4 > Saves If your data is corrupted or you want to revert to a previous save, The Sims 4 automatically stores numerous save points for you to choose from.