All OSes (android, ios, blackberry) require an account. This way purchased apps are linked to your account so you can install them on another device (with the same account).
If you forgot your password follow this link: https://account.live.com/resetpassword.aspx
If you still can't figure it out just create a new account but all apps purchased with the old account will have to be repurchased, and your emails and everything will be lost.