Steam Help Please

[Apem]

Hi,

Ive just got mafia 2 and it had me unistall steam from my pc and reinstall it, the problem im having is now ive got steam back on my pc all my games on steam are saying to reinstall but I have them on my pc already. So how do I get them back on steam without having to reinstall through steam for hours when they are already on my pc please?

Thanks

 

[Apem]

Im really lost I cant seem to find my steam games at all I didnt delete them from my pc just the steam client, when I run them on steam all they want to do is install.