Hey there!

Have you tried Ctrl + Shift + B? That should "unhide" the bookmarks toolbar. Hope that helps!

Bithiah

This does not solve the problem. The screen just flickers and then stops.

Make sure toolbars like the "Bookmarks Toolbar" are visible. Open the Customize page and set what toolbars (Show/Hide Toolbars) and toolbar items to display.

• Right-click empty toolbar area => Customize
• "3-bar" menu button => Customize
• View -> Toolbars
  *you can tap the Alt key or press the F10 key to show the hidden Menu Bar temporarily

• check that "Bookmarks Toolbar Items" is on the Bookmarks Toolbar
• if "Bookmarks Toolbar Items" is not on the Bookmarks Toolbar, drag it back from the Customize palette to the Customize page to the Bookmarks Toolbar

• if missing items are in the Customize palette, drag them back from the Customize page to the toolbar
• if you do not see an item on a toolbar and in the Customize palette, click Restore Defaults in the Customize palette window to restore the default toolbar set.

• https://support.mozilla.org/en-US/kb/customize-firefox-controls-buttons-and-toolbars