I'm sorry if this is a duplicate request for support.

I'm sorry if this is a duplicate request for support. I'm not sure that I posted my question in the correct place.
Suddenly, the calendar is no longer working.
I get nothing when clicking on available time slot.
I deactivated plugins but the issue persists. I uninstalled and reinstalled the appointments+ plugin and I still have the same problem.
Nothing changed except for the fact that I attempted to add some php code to the functions.php file--which gave me an error. I removed the code to get my site back but now the calendar is not working.
The calendar page is here:
http://classesforwebdesign.com/make-an-appointment/
This is really frustrating since I've spent a lot of time learning how to put all of this together.
I activated the 2012 theme in preview mode and the problem seemed to be fixed. If that means it is my theme, then I don't know how to find out where the problem is exactly.