Bookmarks are a way for you to store and manage popular websites you visit directly within the Firefox Internet browser. If you have to reinstall Firefox, you may lose some of your personal data. However, Firefox creates backups of your bookmarks regularly. You can restore Firefox's bookmarks to a previous set of bookmarks if you recently reinstalled Firefox on your computer.
Select "Bookmarks" from Firefox's menu bar.
Click "Open Bookmarks" to open a new window where you can manage Firefox's bookmarks.
Select "Import and Restore." A drop-down list will appear with all of the backups of the bookmarks Firefox has made on the designated date.
Select the desired backup from the list. You can also browse to any manual bookmark backups you have made through the "Choose File" option. The bookmarks should now be restored within Firefox.