Hi, It appears from your question, that you are using Firefox Sync as a back up service. This is not what Sync is designed to do. The Firefox Sync service takes a copy of the data you wish to include and transfers it to a second device (typically a mobile device such as a tablet or a telephone) running a copy of Firefox. The storage in between all attached devices is both temporary and fragile and is not stable enough to be (and is not designed as) a reliable backup service. That being said there is no way to recover your information data. Firefox Volunteer Support provides information only. As far as I know you are the only one able to access your data, if it is not there then it is gone. Please let us know if this solved your issue or if need further assistance.