You can logged in before, but you cannot log in now?

 that is because we just know that your e-mail is not valid. Let say your log-in e-mail is loveyou123456@yahoo.com that e-mail address is not valid because when we tried to send you e-mail message, we get a response from yahoo that say "No such e-mail account." So we disabled your account until you give us your valid address. Change your e-mail to a valid one, the one that you can send and receive e-mail from us.