• If, on Windows, in Firefox 3.6 the menu bar is hidden then press and hold the Alt key down or press F10, that should make the "Menu Bar" appear
• Go to "View > Toolbars" and check-mark "Menu Bar" with a click on it to make that permanent. See Restore the Menu bar in Firefox).
• Make sure that you have the "Navigation Toolbar" and the "Bookmarks Toolbar" visible: "View > Toolbars"
• If items are missing then see if you can find them in the "View > Toolbars > Customize" window
• If you see the item in the Customize window then drag it back from the Customize window to one of the toolbars.
• If, in "View > Toolbars > Customize", you do not see that item then click the "Restore Default Set" button

See also Back and forward or other toolbar buttons are missing and Customize Firefox controls, buttons and toolbars See http://kb.mozillazine.org/Toolbar_customization

Thanks for the info. I have done all that you suggest with no success. I am thinking of uninstalling Firefox and reinstalling. I don't know what else to do. The only thing I have is the Navigation toolbar and a few icons on the bookmark toolbar. Everything else is blank.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems