unable to customize on Highend

My site was destroyed after Revolution Slider issue in December. I am trying to correct it, web master unable to upgrade the slider. I have finally worked out how to do that.But my site has so much info missing and I cannot use Customize as I am getting a message panel on the right saying my session has expired and need to login again.

I believe my site has been hacked with the slider issue.. Tried to login in that message panel for it to reissue the same panel without logging in..

Pulling my hair out as my I am trying to fix this issue myself. Has anyone else had this problem?