After installing the Firefox browser on your computer, if you add or enable the “Bookmarks Bar” in the Firefox>Options button, you can see two default smart bookmark folders displayed in the Bookmarks bar: “Most Visited” and “Introduction”. If you have inadvertently deleted these bookmarks, you can retrieve the most visited one easily.
To restore the Most visited bookmarks folder in the toolbar
1. Visit the about:config page in your browser.
2. Find the preference “browser.places.smartBookmarksversion” double click on it and enter its integer value as (zero) ‘0’.
3. Restart the browser.
The Most Visited smart bookmark will now appear again in the bookmark toolbar, but not in the Getting Started toolbar, which you can access at any time from the Help menu.