I incorrectly overwrote the IMAP and SMTP passwords in settings on my iPad. This effectively deleted the passwords. As I have no note or memory of those passwords I have been unable to reinstate them and therefore cannot send or receive emails on my iPad or my iPhone.
I do have access to my Virgin Media account and, as you say, this enable me to change my email password and my Virginmedia password. It does not show me how I can change my IMAP and SMTP passwords in my iPad or iPhone settings.
Perhaps this is a question for Apple, not Virginmedia?