Do you mean that the location bar (address bar) where you type the URL (address) of a website is missing? Make sure that you do not run Firefox in full screen mode (press F11 or Fn + F11 to toggle; Mac: command+Shift+F). *https://support.mozilla.org/kb/how-to-use-full-screen If the menu bar is hidden then press the F10 key or hold down the Alt key to make the menu bar appear. Make sure that toolbars like the "Navigation Toolbar" and the "Bookmarks Toolbar" are visible: "View > Toolbars" *Open the Customize window to set which toolbar items to display **View > Toolbars > Customize **Firefox > Options > Toolbar Layout *If missing items are in the toolbar palette then drag them 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 *http://kb.mozillazine.org/Toolbar_customization *https://support.mozilla.org/kb/Back+and+forward+or+other+toolbar+items+are+missing

Solved. The "View/Toolbars" menu contains the "Navigation Toolbar" switch which re-installed the URL window. Many Thanks. I would not have found that myself. -rpering

You're welcome