The error is login to server imap.comcast.net with username vimills@comcast.net failed. It also requests a new password at times. The passwords are correct and have not had problems until now

MY thunderbird email comes from my comcast email. My wife email account will not allow a login. This account has been working for many years with no issues. The error is login to server imap.comcast.net with username vimills@comcast.net failed. It also requests a new password at times. The passwords are correct and have not had problems until now