Hi grace.henderson, I'm sorry to hear about this problem. I don't have any experience with merging Firefox Accounts, but usually data loss occurs if you need to reset a password. Was that involved in the process in any way? For your local installation, how did you uninstall Firefox? As long as you didn't remove your old profile data, it should still be on disk. Could you check whether your stuff is available in a different profile, as follows: '''Profile Manager Page''' Inside Firefox, type or paste '''about:profiles''' in the address bar and press Enter/Return to load it. This page should list at least one profile and could list many. (Each profile has two folders and one or more buttons. Do not use any Remove buttons!) The profile that Firefox is currently using will have this: '''This is the profile in use and it cannot be deleted.''' Do you have another profile named '''default''' or '''default-release''' or default-''longnumber'' listed on this page? If so, you can check whether it is the one you were using recently by clicking its '''Launch profile in new browser''' button. If it isn't what you want, simply close that new window. If it IS what you want, back on the about:profiles page, click the '''Set as default profile''' button for that profile so Firefox uses it automatically at the next startup. If Firefox says it can't "downgrade" that profile, it may be simpler to copy a few files over rather than trying to do that. (Details if needed.)