ATT lost my original mailboxes

Using Yahoo for many years on a mobile and desktop. Recently the desktop no longer shows my Yahoo mail using Chrome. Instead it shows a mailbox I've never used -- xxx@att.com . I was able to load the yahoo.com mail on Edge, but now the yahoo account won't show up on Edge either. I can still get Yahoo messages on my mobile but can't read email on my desktop now. 

(Edited per community guidelines) has happened?