Hi

I am sorry but if you change your Firefox Account password while data is being synced between copies of Firefox, that data is erased.

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.

If you have a copy of your Firefox profile for desktop Firefox, you may be able to recover your bookmarks and other data. Please have a read of this article.

If you have a copy of your data on a mobile version of Firefox, please follow these instructions to connect it to Firefox Sync to copy your data.

Resetting the password of the Firefox Account because you do not remember the password will remove all data stored on the Sync server. This is because this password is used to encrypt your data before it is uploaded to the Sync server and only this password or a possible recovery key can decrypt this data.