Apple ID page says user name on itunes on PC is not a valid user name
Itunes on my PC uses an old email address as user name. I do not remember password and when I go to "forgot my password" and put in user name, it tells me there is no such user name. I have changed the user name/password on all of my other Apple accounts (icloud, I Phone 6, I Pad, App store, etc) to a newer email address. How do I change the user name on ITunes on my PC?
null-OTHER, Windows 7, itunes on a PC using windows 7