Have you lost individual icons or whole toolbars? In Fx4 the Menu Bar is hidden if you have the new orange Firefox button in the top corner. Right click on toolbars space and check Menu Bar to restore. Use customize to move icons if they are on the Menu Bar to the Navigation Bar, if you wish. The Status Bar has gone but can be replaced by an extension. If this is your problem you can always toggle the Menu Bar. If you check through the options of your extensions you may be able to re-locate icons. This is a way in which you might be able to restore lost icons. If you have "lost" buttons(Home, Refresh, Stop etc), too, you should check in the Search Firefox Help box above.