Sorry to hear about your data loss. I will address Firefox since I am less familiar with Thunderbird: Are you running Windows? Sometimes after updates Windows starts up in a state where Firefox doesn't have normal permissions and you only see incomplete settings. If you haven't shut down Windows and started it up again since this problem occurred, I would try that first. If that doesn't help, could you check your desktop for a folder named Old Firefox Data? If the Refresh feature ran, Firefox would have moved all your old settings into that folder and we could use it to roll back to refresh. Do you see anything like that? If you check inside, were the contents updated recently? If you don't see any evidence of a Refresh, have you noticed any strange behavior in Firefox recently? Perhaps that would help in understanding what might have gone wrong. Also, have you used the Windows "system restore" feature recently? That can unfortunately wipe out your Firefox data.