Several reasons can cause Roadrunner email not working, such as incorrect login credentials, server downtime, or outdated app versions. To fix this, first, ensure you're entering the correct email and password. Next, check for any ongoing server issues by visiting the Roadrunner website or contacting their support team. Finally, update your email app or switch to a different app, ensuring you've entered the correct IMAP/POP and SMTP settings. Clearing your browser's cache and cookies can also help resolve access issues.