Windows Live Mail Problem

I have a friend who uses an Acer laptop recently updated to Windows 10 from Windows 7.

Several weeks before, he lost the ability to log in to his Windows Live Email. When he clicks on WLM desktop icon, a box entitled Mail comes up with the message “Sorry there was a problem signing in”. There was an OK and Cancel button at the bottom. 

Clicking OK brings up “WLM Sign In” box. It asks for the email address and password then to click on the Sign In button. There is a link underneath asking for Windows Live ID. I am told my friend does not have one but when he clicks on the Sign In button at the bottom, the Mail box referred to above comes back.

I have read other posts similar to this but they not being quite the same, has anyone any suggestion please on how to get over the problem.