You went through the whole process? Like, saving your saves, mods and tray in a safe, separate area (maybe on an external hardrive if necessary) and trying to play the game vanilla?
As long as your saves are backed up properly, you shouldn't lose them. You just need to make sure you have back up copies.
If you did do all of that, then don't be too nervous about trying to reinstall. As said, as long as you keep your files backed up somewhere else other than your Sims 4 folder, they should remain safe. Just make sure that when you put them back into your game, it is only a copy of them and that the backup still has all of your important content.