I'm not really sure what happened, but it was server side and affected another few of my sites as well. I opened a ticket went it went down but had to go out. When I got home, they had replied "Which domain?" - so that wasted like 3 hours. I won't comment on how I think that should have been handled.
Once they told me the issue, I was able to go and get them all back up. Somehow, something on the back end caused a few lines to be written in the htaccess files of multiple sites, and these lines prevented any "PHP" links to work, which this site basically runs on PHP/MYSQL.