Make sure that you do not run Firefox in Full Screen mode with all toolbars hidden.

• Press F11 to toggle full screen mode (Firefox/File > Full Screen)

If the menu bar is hidden then press the F10 key or hold down the Alt key, that should make the menu bar appear.

I used force quit to totally shut firefox down - restarted and the enu bar was there as well as access to my dock which had also been inaccessible...Thanks for trying to help..

maybe you pressed the F11 button by mistake. Press it again the menu bar should come back.