Safari plug-ins - unblock
Try restarting Safari with the shift key held down. Try going to Safari/Preferences/Websites and uncheck all Plug-ins. Quit and reopen Safari. If Safari works normally, recheck them one at a time until you find the problem. Quit and reopen Safari after checking each one.
If the above doesn't work, go to your hard drive level Library/Internet Plug-ins and move them to the Desktop. Restart Safari. If that works, copy the Desktop files back one at a time until you find the problem.
If still no luck, make your user Library visible and repeat the above. Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J. When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder. Select Library/Internet Plug-ins.