hello, i'm sorry for the issues you're having, but the sync feature wasn't created as a backup facility in mind but rather to keep multiple devices on the same level. during the setup of the sync accounts you were asked to print/save the recovery key to the account. without it - or in case you've already reset the recovery key - it won't be possible to access the synced data unfortunately. since sync can hold very sensitive information like all the user's passwords and browsing history it is of paramount importance that the data is properly encrypted. normally when you let users choose a password freely they tend to use rather weak passwords, that's why the recovery key was introduced which should guarantee strong encryption standards. mozilla is aware of those usability issues with sync though and will likely come up with a replacement in the future...