So I had to wipe out the computer that I had sims on. Unfortunately, that meant that I had to install all my mods back in again. I followed the instructions for self installation, but when I went to look for the TS3.exe file, it wasn't there. The game won't start now. I'm sure that it was there before I started with mods because the game started before. Is this an issue with a mod I installed or is it a game problem that I am going to have to reinstall the whole game?

Can we assume that "wipe out the computer" means that you reformatted your disk?

If you reformatted your hard drive, then you have to reinstall the game before installing the mods.

This is a game problem not a site issue. Moving to help!

If, in fact, you formatted the disk (wiped out the computer) you need to:

1. Reinstall the game(s) and patch accordingly, see Game Help: TS3 Patching
2. Install the Framework - see Game Help: Installing Sims 3 Package Files

Simply installing mods will not remove the TS3.exe file. Are you looking for it in C:\Program Files\Electronic Arts\The Sims 3\Game\Bin folder and not under ...Documents\Electronic Arts\The Sims 3? Do you have the Base Game only or also World Adventures, High End Loft Stuff and what version is your game?

What exactly does "the game won't start" mean? You click to start the game and nothing happens? it starts to load and stops? it starts to load and then goes away? You mention "I'm sure that it was there before I started with mods because the game started before." meaning you did test the game before attempting to put custom content back in?