How do I fix a game that a mod has messed up?

[Bullseye]

I installed a few mods from comminity guids in C:\Program Files (x86)\Steam\SteamApps\common\Grand Theft Auto Vice City & game started freasing at loading screen, I've tried deleteding modds & local files & reinstalling the game, verifying game files & steam://flushconfig command from run, all to no availe, I thought it could be something I need to do in regedit or it was cloud setting but game dose not have cloud function. what do I have to do to wipe a game from steam for reinstall so it is as if it were never there so I can reinstall & game will work again? I really don't want to uninstall steam, (unless I can keep games installed?) or format my computer.

[ronr42]

You need to manually delete everything in the Steam Apps/common/ GTA game folder and re-download again.

[Silicon Vampire]

http://steamcommunity.com/discussions/#games