Customizer won't load in Coraline 1.5

Hello. I tried to change my header at http://wapshottpress.com today and when I did what I usually do (click on Header in Appearances)it opened The Customizer and nothing loaded/populated/whatever it is the left sidebar below it. So I couldn’t even get to the header to do anything to it.

I checked another Coraline install that has WP 4.1 and Coraline 1.4.2 and that works, so I’m stumped and here. I tried uploading the 1.4.2 into wapshottpress.com themes, to get it to revert to 1.4.2, but either it didn’t work or I didn’t do it right, because I still have the same problem.

I host on Dreamhost and am very lucky there so far. The database is updated, I’ve tried it in Firefox, Chrome, and SeaMonkey browsers and had the same problem. SeaMonkey showed it “loading” but after 10 minutes of loading, I gave up. I tried reverting to the previous version of WP and got a 401, 408 or possibly 403 YOU DON’T HAVE PERMISSION, peasant, message (sorry it was too scary so I didn’t look at it very long), and I have googled as hard as I can to find a solution to this before asking here. I’d be much obliged for any help on this. Thanks.