Hi If you still have a copy of you bookmarks in a version of Firefox (for example on a mobile device) and you sign into Sync in the reinstalled desktop version, the two should connect and a fresh copy come through. Firefox Sync is not a "cloud" backup facility. If you want to have a backup of your bookmarks, I would suggest either [https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer exporting] them to a file or making a [https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles back up] of your Firefox profile. If you still have your old profile on your computer from your previous installation, you should be able to extract the bookmark file and move it to your new profile. This [https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data#w_what-information-is-stored-in-my-profile article] will help you identify the files that you need from your old profile.