ATT/Yahoo Email

This unmerging of AT&T and Yahoo is a mess.  Before my account was unmerged all was fine.  I have had the account a number of years.  After the unmerge, I could not log on.  I talked to AT&T support several times and was told to just wait and it would be fixed.   Then "A MIRACLE" I was able to log on to the ATT.NET website.  The 2 days ago, it suddenly quit working again.  When I try to log on to att.net it redirects me to the yahoo account and  I can't log in there.  My password was working up until 2 days ago.  I have not changed it.  I have done everything you all suggest.  Update Java, use different browsers, make sure Adobe Flash is up to date, clear my browsing data.   

The above concerns my computer.   On my phone when I try and set up the AT&T account it says I have the wrong password.  So no matter what I do I am screwed.  Somebody, please help me.