Make sure that toolbars like the "Navigation Toolbar" and the "Bookmarks Toolbar" are visible.

   Firefox menu button > Options
   View > Toolbars (press F10 to display the menu bar)
   Right-click empty toolbar area 

Use Toolbar Layout (Customize) to open the Customize window and set which toolbar items to display.

   check that "Bookmarks Toolbar items" is on the Bookmarks Toolbar
   if "Bookmarks Toolbar items" is not on the Bookmarks Toolbar then drag it back from the toolbar palette into the Customize window to the Bookmarks Toolbar 

   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 setup 

You can check for problems caused by a corrupted localstore.rdf file.

   http://kb.mozillazine.org/Corrupt_localstore.rdf

Did you reset Firefox?

• https://support.mozilla.org/kb/reset-firefox-easily-fix-most-problems

When you reset Firefox then a new profile is created and some personal data (bookmarks, history, cookies, passwords, form data) is automatically imported and the current profile folder will be moved to the desktop to an "Old Firefox Data" folder.
Installed extensions and other customizations (toolbars, prefs) that you have made are lost and need to be redone.

It is possible to recover specific data from the old profile, but be cautious not to copy corrupted files to avoid carrying over the problem.

• https://support.mozilla.org/kb/Recovering+important+data+from+an+old+profile
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox