Cannot read any emails downloaded recently into Windows Live Mail 12

Since 13th September I have been unable to access my emails via Live Mail 12.

1) I have been unable to download emails from my POP accounts, and get the error message:

Unable to send or receive messages for the Main email account. An unknown error has occurred.

Server: 'mail.madasafish.com'
Windows Live Mail Error ID: 0x800C013E
Protocol: POP3
Port: 110
Secure(SSL): No

2) I have been unable to read gMail emails which have downloaded. In each one, the reading pane displays the message:

Message could not be displayed

Windows Live Mail encountered an unexpected problem while displaying this message. Check your computer for low memory or low disk space and try again.

3) I cannot send emails. I get the error message:

The email could not be sent. A problem has occurred. Please try again.

There is plenty of disk space and memory.

All problems started after 13th September, so it's not a problem external to my PC. I seem to remember it was after an OS update, but there isn't an update on that date or the day after listed in the Control Panel.

How do I get my emails back? Any help appreciated. Thank.