Other people aswel as myself have found that even after creating a mygov account and having the new password new & fresh in your mind, try to log in with our password...
It will NOT let us log in, no matter how many time you check, and knowing 100% that the password entered is correct, for some stupid reason mygov returns with the wrong password error. Then only giving you 3 tries, mygov then gives you the error message saying that your mygov account is now locked, you need to create another account, What an inconvience!
This seems to happen to everyone I know thats tried to log in to mygov, it gives me the impression that its done on purpose, and I have always known from a previous Centrelink worker that everything is set up in a way to put people off applying for centrelink payments.