server error when I try to access widgets in Platform

I’ve been trying to access my widgets in my platform site, but every time I click in the widgets link, I get an error message that says “HTTP Error 500 (internal server error).” I really need to change some things in the sidebar. Here is my site: https://www.luckystarfashion.com/blog/

I can’t run the updates, right? That would “erase” all the changes I made to the site. Any advice would be great!