I got hacked... Probably a while ago.

I have really been having a go of things lately. My site appears to have been hacked and honestly it was probably a few months ago. I just completely forgot to take care of the problem. People have seen Levitra and Cialis ads through Google and sometimes are redirected to the iPhone App Store. Is there a way to scan what is causing this?

Are there affordable solutions so someone can do this for me? Godaddy suggested sitelock but said that if it is in the database, they may charge up to $500!

Help please. If it's in the theme files, I assume I just reinstall the theme? If it *is* in the database, what are my options?