After Firefox updated itself I lost all my important bookmarks, how to get them back?

Do as you want. Please look for a Folder on the Desktop called OldFirefoxData if there good, If not look here : *https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data Note the dates of the folders *https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles You can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over the problem. Never work with original files. *https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile *http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox fyi for future : *https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles *https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer Please let us know if this solved your issue or if need further assistance.