You may lose access to your account if you lose access to your authentication app (Google Authenticator, Authy, etc). For instance, if you’ve deleted the Authenticator app or lost your phone. You can try to regain access with a backup key if you saved it at the moment of 2FA registration.
If you have no backup key, please email email@example.com from your account email address. You’ll need to fill in a form with questions so that we can verify you and temporarily disable your 2FA. It will help you to log into your account and realign your two-factor authentication.