I Can't Access My Yahoo Account!

Ok so somehow my old yahoo account linked to my att.net account and I forgot the password to the yahoo account. When I try to reset it, it sends me to the att.net reset page and says they sent me a temporary passwork to the yahoo account WHICH I CAN NOT ACCESS because that is the only one I am interested in getting in to. I've spent way too much time in this loop already and would like to know how I can either unlink the accounts or just answer my security questions for the yahoo one. ATT should NOT have to pop up when I am clearly on YAHOO trying to solve a YAHOO problem.