How To Backup Your FireFox Bookmarks
Like everything else with computers, if you do not have a backup when your PC crashes, you will
lose everything. For everyday applications such as browsers, backing up your bookmarks does not require a complete hard drive backup to keep them from being completely wiped out.
By default Firefox backups your bookmarks automatically when it is closed to C:\Documents and Settings\[your username]\Application Data\Mozilla\Firefox\Profiles\[profile name]\bookmarks.bak. To restore, just rename to bookmarks.html.
Firefox will also archive, by default, the last five saves to the bookmarkbackups folder at the same location. The number of times it archives, can be modified by typing in the address field: about:config and changing the value for browser.bookmarks.max_backups.
You can also export your bookmarks with Bookmarks Manager.

