Make use of this and give a try..

• https://addons.mozilla.org/en-us/firefox/addon/auto-sort-bookmarks/

Hi F.blake,

In the Customize toolbars window (View > Toolbars > Customize) press the "reset to default" button.
Links come back. Then you can recustomize your toolbars as usual.

Open the Customize window to set which toolbar items to display:

• Firefox > Options > Toolbar Layout
• View > Toolbars > Customize

• Check that "Bookmarks Toolbar items" is on the Bookmarks Toolbar
• If the "Bookmarks Toolbar items" is not on the Bookmarks Toolbar then drag it back from the toolbar palette in 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 set up

• https://support.mozilla.org/kb/How+to+customize+the+toolbar
• https://support.mozilla.org/kb/Back+and+forward+or+other+toolbar+items+are+missing

• http://kb.mozillazine.org/Toolbar_customization