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. Make sure that toolbars like the "Navigation Toolbar" and the "Bookmarks Toolbar" are visible: "View > Toolbars" * If items are missing then open the Customize window via "View > Toolbars > Customize" or via "Firefox > Options > Toolbar Layout" (Windows) * If a missing item is in the toolbar palette then drag it back from the Customize window on the toolbar * If you do not see an item on a toolbar and in the toolbar palette then click the "Restore Default Set" button to restore the default toolbar set up. See also: * http://kb.mozillazine.org/Toolbar_customization * https://support.mozilla.com/kb/Back+and+forward+or+other+toolbar+items+are+missing

Pressing F11 solved the problem. Thanks!

You're welcome.