Fatal "this page isn't working" errors, site suddenly non-functional

Hi there, I am using elgg 2.3.3, Version - 2016092300

I'm having a huge issue with my elgg site. Recently my server host's VPS went down, and when they 'fixed' the issue, the site returned but is no longer working properly.

I am unable to access the plugins page, I am receiving a "this page isn't working error, unable to handle the request, http error 500". I assume there is a plugin causing an error but I don't know which? 

I am unable to edit or delete posts, and if I try to save my settings in the admin panel it brings me to the same 'this page isn't working' error. Before the server went down I changed the default access permissions to "logged in users". I cannot change it back because saving causes the fatal error issue. Is there another way I could try to manually override and return default access permissions to "public" to see if that might be a cause of issue? 

I am unsure what to do. I only have minimal experience with php and mysql, my knowledge doesn't go beyond that.