* Simply go to your "Help" tab in FF.
   * Select "Troubleshooting Information" from the drop down menu.
   * Under the "Application Basics" heading click on the "Open Containing Folder" button.
   * In the file explorer window that opens up, select the "Type" header to put the files in order
   * Look for any files of that type named places.sqlite, places.sqlite.corrupt, places.sqlite-journal or places.sqlite-journal.corrupt.
   * Rename or delete these files.
   * Close the window.
   * Restart FF and it will regenerate new non-corrupt places.sqlite and places.sqlite-journal files.
   * In the FF Menu Bar click on "Bookmarks".
   * From the drop down menu select "Organize Bookmarks"
   * In the new window select "Import and Backup" from the menu bar.
   * Hover over the "Restore" button then move your cursor over the fly-out menu.
   * Finally, click on the date of your last know good backup file. 

You may have corrupted your your places.sqlite and/or your places.sqlite-journal files. * Simply go to your "Help" tab in FF. * Select "Troubleshooting Information" from the drop down menu. * Under the "Application Basics" heading click on the "Open Containing Folder" button. * In the file explorer window that opens up, select the "Type" header to put the files in order * Look for any files of that type named places.sqlite, places.sqlite.corrupt, places.sqlite-journal or places.sqlite-journal.corrupt. * Rename or delete these files. * Close the window. * Restart FF and it will regenerate new non-corrupt places.sqlite and places.sqlite-journal files. * In the FF Menu Bar click on "Bookmarks". * From the drop down menu select "Organize Bookmarks" * In the new window select "Import and Backup" from the menu bar. * Hover over the "Restore" button then move your cursor over the fly-out menu. * Finally, click on the date of your last know good backup file. Your Done!