If you can't log in, there are a few steps we can take. First off, if you set up password recovery in the past, then this process will go much, much smoother.
If you did, then you would have sent yourself an email with a recovery link (the subject of the email is "Ember Recovery Link") when you first set up the feature. I'd recommend scrolling back or searching in your inbox and clicking on this link to start the recovery process. There's a small hint in this email for your username as well.
If you are on your original device, you should also see a dropdown showing past usernames on the Login page. Once you click on your username you should get redirected to Touch/Face ID login and you'll be all set.
Please note: We do not store any username/password and do not have any access to your crypto/account on our end - make sure you have written your credentials somewhere safe.