In my experience, your user files don't get deleted when you reinstall the game. This is why your old "The Sims 3" folder in your Documents still exists. Rename that folder something like "The Sims 3_Old" and start your game up, as Karritz said, and the game will create a new, fresh "The Sims 3" folder.
As for your CC and Mods not showing up: did they work before? Or are you just now trying mods for the first time? Either, I can make a quick tutorial to help you set that up properly.
As for expansions not showing up: I'm not sure, but my first thought if this was me was to verify that they're installed. :lol: In your launcher under "Expansions & Stuff" at the bottom of the page it should say Don't see your packs? click the "Install Packs" button next to it.
