Urgent – Update Problem

Hi,

Today I find a update of the theme launched, then I follow the instruction that installed the envato plugin to my wordpress. After that, it showed the theme version 1.5.7 is available, then I choose update, however, it showed fail to update. Then the problem occur, I found that “theme option” disappeared and the website can’t work that show “500 internal server error”. What should I do?

Best Regards
Eric