I hope the below thread will help you out: https://support.mozilla.org/en-US/questions/1227757

''<p>djtennett [[#question-1327861|said]]</p>'' <blockquote>Are the bookmarks stored at Mozilla? </blockquote> Maybe? Many users have been able to recover bookmarks from other installations of Firefox through the Sync feature. If you had connected your old installation of Firefox to a Firefox Account and allowed it to sync your data, then that would be an option for you. Your bookmarks and other data you Sync would have been encrypted with your Firefox Account password. However, using Sync as a backup/restore service doesn't always work: sometimes when the original Firefox installation is unavailable, the new one doesn't successfully access its data.