WordPress 4.4_GB Widgets not working

I updated this morning to 4.4 as recommended.

I now cannot add new widgets or move my current widgets around.I can see the little cross when I hover over a theme, but if I drag or use a new widget, the writing just goes blue like when I am highlighting a text.

I shut off all the plugins, reinstalled, and switched my theme to Twenty Fifteen.

I tried to find twenty sixteen but when I go to the look for new theme page, all is blank. I still have the menus etc but no themes to choose from.

Please help.

Peter