See the following article: [[Restore bookmarks from backup or move them to another computer]]

Did you uninstall Firefox and also removed your personal data? When you remove personal data when uninstalling Firefox then all profile folders with your personal data including the bookmarks have been removed. You would need an undelete utility if you do not have a backup. *Recuva: http://www.piriform.com/recuva *https://support.mozilla.org/kb/Recovering+important+data+from+an+old+profile *http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox