I am in a foreign country and cant login to my account

I am now in a foreign country. I have lost a lot of memory because of a traffic accident before. I don’t know how to log in to my ATT account with my original ATT mobile phone and a mobile phone SIM card with no signal while abroad?  I forgot my original account and password!  I can't talk anymore... I only know that it is ATT by reading the information in the phone!  Please help me...