For the last 3-4 months I cant access one of my email accounts (I have two but one works fine) withough having to sign into BT Yahoo.
Also, when I have been signed into Yahoo for a while, I cant access the email account again though MS mail - its almost like it times out?  All I keep getting is an error box asking for my password which it wont accept (I have never changed it!).  It just keeps going round in circles.

I even uninstalled mail but when I reinstalled it - it was the same. 

Im not technically minded and am starting to lose the will to live.  HELP!!!