email problem

Suddenly my [email scrubbed] is unusable. I cannot receive or send email. One device says username or password is incorrect. I try to change and am not allowed to do so. Other devices say my account cannot be verified. I can login to att.com with the same username and password. This suddenly happened and att customer service has just gone in circles. If I try to change password they send information to my [email scrubbed] which I cannot access. Very frustrating. Thank you in advance for any help you can give me.