Well, all your maps, skins, settings, etc. will be deleted. But you will not lose your games, youll just have to reinstall them. If the steamapps folder is missing, and you start up steam, it'll auto generate the steamapps folder.
oops i meant my tf2 folder in C:\Program Files\Steam\steamapps\*name*\team fortress 2 folder... if i delete that. Will all of my weapons and how long i played will all that be deleted?