Thunderbird is not accepting password for emailing my family that it used to.

It isn't thunderbird rejecting it; it's roadrunner. You might try this:, it - click to settings>privacy&security - click saved passwords and then show passwords - then, highlight the rows for that one account and delete them. that removes the old password - now, when prompted for password, it may work

If not, post screenshots of the server settings pane and the SMTP server settings pane and someone here may have suggestions. OR, you could visit the roadrunner website to see if the settings for email clients has changed. This sometimes happens as providers tighten security.