Avoiding account lost issue by binding email and you can use email to retrieve password if you forget password. Check the picture, follow the steps. You need to logout first before you bind.
1. It only works for the current default Quick Start account or Facebook Connect account. For example, if you have a quick start account character name is A, but you cannot find it anymore, then you tap quick start again and open another account on the latest server. This binding won't find your Character A back, but it will bind with the latest account you just created.
2. If you use quick start or Facebook Connect at first, it means you did not create a username and password for your account. The name shows on the top left on the game is your Character name (Name in Game) not username for login.
3. If you are a Facebook Connect or Quick Start user, when come to the fourth Step, don't put anything to the username box, just leave it blank. Then you put the email you wanna bind, and the password you wanna use.
4. When you finish all four steps, you will see a notification says like "Send an email to your email box", so you need go to your email box and click the URL link inside the mail. That's the final step-- Activation. Now you can use your email address as username to log in.
5. For WP8 user, the third Step shows "Set Email" instead of "Bind Email"
P.S. for the register user (use username and password to login) steps are all the same, except put your username in the username box when comes to fourth Picture. And your password is what you registered name use to login (must be the same).