I have been having an issue with steam.

I just downloaded just cause 2, and tried to play it. It said the game files were corrupt and I followed steams supports suggestions to fix it. I messed up. It wont even let me into steam since i tried to make a new clientregistry.blob folder. I also tried to change the setting of steam to read only through properties, but it just made it worse. Help? Please? I dont want to have to reinstall all my games, so itd be helpful to have some assistance.