94 Tercel Need Bolt Information

My girlfriend has been driving her toyota tercel and its been squealing whenever she tries to turn on the air conditioner but runs fine without it. Seeing as how it's so hot in louisiana during the summer, its almost impossible to drive without air conditioner unless you like sweating. Today, I popped the hood and found out that the bolt that connects the pulley to the engine is missing and the pulley is tilted a little bit and I can't seem to figure out how to even get the belt off the pulley to try to make it level to find out what kind of bolt I would need. Went to an auto parts store and they said they don't know what size bolt I would need, that I would have to figure it out, and I would also need to know how to fix it, can anyone help on this? Also attached is an image of what I'm talking about.http://i41.photobucket.com/albums/e265/rheinpfalz/IMG_4156.jpg

I would go to a Toyota dealer and get the bolt from them. You can point out the bolt on an exploded parts diagram and get the right one the first time.