Yahoo email will not take password-it sends me over to at&t

Hello,

Yahoo requested a new sign in(again) and after I put in my email
Address the next page becomes at &t which is part of my address
But I have nothing to do with at&t.I had a chat with at&t and they
Said nothing was wrong with my email and problem is with yahoo.
There is no comparable problem I can find. Each time I try to put
In my password,it flips to at &t.