If the audio or video lectures in the Content tool are not playing, this is most likely the result of a missing plugin needed to play the audio or video. To check whether this is the issue, complete the system check found on the login page before logging in. Ensure that all plugins are enabled and update any programs if required (such as Java, Adobe, etc.).
Restart the browser and try playing the audio or video lecture again. If this did not solve the problem, contact your instructor and inform them of the issue.