Theme Customizer Not Loading

I’m having problems customizing the theme I have installed on the site I am working on. (Catch Base, free version) It just won’t load in the “Customizer” at all, even though it worked fine up until a couple of days ago. I just get a blank menu with a mostly blank left side panel. I have tried re-installing the latest version of wordpress, and I’ve already tried installing other themes only to discover the same thing happening.

Please HELP!!! I have some deadlines looming!!