Hello,
I had fix all the 500 errors on your site. Your site is very much missing. So I had to upgrade full code administrator folder.
I check lost file: I downloaded the same version of Joomla core and compare with your code. Find and copare folder, file.
You should be careful when moving and edit core joomla. It can make your website error.

joomfreak

Thank You very much.

Unfortunately it wasn't moved by us but from the hosting provider. They moved from one server to a new one and... yes it could be lost in that moment.

We are very grateful for your help!

Have a nice day