If you have deleted one or more of the default Smart Bookmarks Folders, including:

• Most Visited
• Recently Bookmarked
• Recent Tags

you can restore them by doing the following:

1. In the Location bar, type about:config and press EnterReturn.
   • The about:config "This might void your warranty!" warning page may appear. Click I'll be careful, I promise!, to continue to the about:config page.
2. Search for the preference browser.places.smartBookmarksVersion.
3. Double-click on browser.places.smartBookmarksVersion and change the value to 0 (zero).
4. From the menu at the top of the Firefox windowbar, select FileFirefox and then select the ExitQuit FirefoxQuit menu item.

The next time you start Firefox, the default Smart Bookmarks Folders will be re-created.