Theme seems to have crashed

I have been using the Tempera theme for months and when I went to edit some things today, the entire site crashed. I was able to revert it, temporarily, to another theme. I would love to keep using Tempera, however even the Live Preview will not work, so I am afraid that if I go ahead and activate the theme, I will have the same problem again. I am receiving a Server 500 Error. Any help would be much appreciated.