I’m using Simple Image Gallery Plugin for a while and it is really great. But when I upgraded it to a new version v3.6.0 I have a problem. The thumbnails are showing cool, but when I click to enlarge my image - it is enlarged properly and I start to list other images but soon suddenly everytihng disappears and the white page appears.. only in the upper left corner on my screen is a printed contact email. And this always happens when I open any picture gallery on my site. That problem has not existed before.

The site is: www.arhivvojvodine.org.rs/ but when I update Joomla to v3.6.5 that problem with sig gallery has disappeared. But appeared new.
- I cannot edit or add any article anymore. In the article manager the save and apply button refuse service.
- I cannot edit modules, the screen begins to load, then goes blank except for a small drop down with the name of the module in it.
I ca not do anything in the site administration, just open and close articles, plugins, templates...

Front of the site all fine.