" The RETR command did not succeed. Error retrieving a message. Mail server mail.btinternet.com responded: problem retrieving message."

Have just installed Thunderbird, as fed up with windows 10. On installation Thundrbird received hundreds of emails that I have received in last 8 months, all of which I was in the process of deleting from my inbox, when this error message came up: " The RETR command did not succeed. Error retrieving a message. Mail server mail.btinternet.com responded: problem retrieving message." Now cannot receive any more in my inbox Help