Hi

Thank you for your question about the Firefox Sync service.

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.

First - do not reset your Sync password! If you do that, your data will be wiped from the Sync server. Your data was encrypted using the original password and changing that password makes your data unable to be decrypted, thus useless.

You need to setup Sync on that computer, but as an additional device. https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer

Using Connect additional devices to Sync in that support article. https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer#w_connect-additional-devices-to-sync