1) Click on the bookmarks icon and then Show All Bookmarks in the dropdown menu.
2) In the window that opens, click on Import and Backup > Restore > Choose File.
4) Navigate to your H: drive and locate the backup file. There should be a .html file called "bookmarks" followed by the date your bookmarks were backed up. Select the file and click "Open".
5) Finally click "ok"
Your bookmarks should now be restored in Firefox.