Caution: Restoring bookmarks from a backup will overwrite your current set of bookmarks with the ones in the backup file.
Click the Bookmarks button on the right side of the navigation toolbar (Windows XP: click the Bookmarks menu) and select Show All Bookmarks to open the Library window.On the menu bar, click Bookmarks and select Show All Bookmarks to open the Library window.At the top of the Firefox window, click the Bookmarks menu and select Show All Bookmarks to open the Library window.
In the Library window, click the Import and Backup button and then select Restore.
Select the backup from which you want to restore:
After choosing a backup, your bookmarks from that file will be restored. Close the Library window.