My sister and I have had the same problem a few times.
Go to log into the mog station, password is wrong (no idea how). Reset the password. Password still wrong. Reset the password again. Password incorrect. Reset again. Password works.
Go to log into SE store. Password incorrect. Reset password. Password incorrect. Reset password. Password works.

There was one night I was stuck for an hour trying to log in and my sister had to create an entirely new account with an entirely brand new e-mail address /just/ so she could play. Luckily, the character she had was only like lvl 1 or something but it was still very frustrating for her.

The only time I've had a worse issue with a similar situation was trying to cancel an Xbox live membership and needing to reset the password because I'd forgotten it.