If you have access to your Firefox Account, it's easy to change the email address. Go to the [https://accounts.firefox.com/settings Firefox Account settings page] and add the new email address as a secondary email address. Once you verify that email address, you will be able to make that email address the new primary email address. Once you've done that, your current primary email address (the non-working one) will be the new secondary email address and you can just remove it from the account. However, if you don't have access to your Firefox Account and don't have the recovery code, you are out of luck. You'll have to make a new account in that case. Hope this helps.