Cannot Update Plugins

Since I updated to 4.5.2 I am no longer to update plugins.
I can’t even delete them. Somehow my permissions seem to be the problem but I can’t remember changing them. I havent touched the website for a long time because I have limited support on it.
Users don’t have access to admin or to adminrelated features like plugins etc.

Any Idea what happened here and how to solve the issue without changing lots of permissions?