After installing Firefox browser on your computer if you add or enable “Bookmarks Toolbar” from Firefox button>options, then you can see two default smart bookmarks folders displaying on Bookmarks toolbar they’re: “Most visited” and “Getting Started”. If you’ve unintentionally deleted these bookmarks, you can get back Most visited one easily.
To restore Most Visited bookmark folder back on toolbar
1. Visit about:config page in browser .
2. Find the preference “browser.places.smartBookmarksversion” double click on it and enter its integer value as (zero) ‘0’.
3. Restart the browser.
Now Most Visited smart bookmark will appear again on bookmarks toolbar but not the Getting Started one, which you can access anytime from Help menu.