[baal80spam]

Maybe it sounds silly but make sure you have access to the email associated with your Mozilla account. I learnt the hard way after reinstalling Windows that Mozilla sends a confirmation email to this address when you set up Sync on a new system. It turned out that I had no access to this email anymore since the provider went out of business. I was told it's impossible to access my sync data. Thankfully I did not use it to store any passwords (I use KeePass for that) because otherwise it would have been a catastrophe.

[roter]

There is a "Secondary email" option in Firefox Accounts. You can also set a "Recovery Key".

[jobigoud]

I use keepass as well and there is a similar conundrum. If you store a backup of the keepass file on a remote server, make sure the passwords to access this remote server aren't only in the local machine keepass.

[lucb1e]

Wait but, you had no backups? I don't mean email access or sync access, but simply a backup of your system with your photos, documents, application data (including firefox' password database), none of that?