1. If any of your family member shares the same account, ask them if they might have changed the screen name or password.
2. Look into your email inbox to get the actual screen name when you had registered with Pogo
3. If you find any point relevant to your case, you can go to the article explaining how to reset password of your Pogo account and follow all the steps carefully to reset your pogo account password.
pogo.com/sign in problems