Tools In Illustrator Not Working

I used Illustrator all this morning and everything was fine. Now I can click other tabs and select tools, but none of them will do anything. I have several tabs open and it won't work on any of them. Literally the only thing I can do it round the corners of a rectangle with the direct selection tool. Can't even pan. I would restart the app but I can't even save (CMD+S won't work, all drop down menus are greyed out).

I'm doing client work, so I need to resolve the issue quickly. Has this happened to anyone? How to fix it?