For primary diagnosis, you should re-verify your Username and Password, because they are case sensitive and hence creates trouble if entered wrong mistakenly.
RoadRunner Email Not working - You should ensure to use the new RoadRunner if still finding a problem in login, then you can try to delete the browser history and remove the cache files. At times, accumulated data also creates a lot of trouble, switch to a different browser to solve
RoadRunner Email Not working issue.