Hello hmtft,
Welcome to the HP Forums.
I understand your microphone is not working. I am sorry for the late response, but I will do my best to assist you. I will provide an HP document with troubleshooting steps you can try to help resolve your microphone issue: Resolving Microphone and Line-in Problems (Windows 7)
I provided a Windows 7 document because this computer comes with Windows 7. If you have a different operating system, please let me know. Also, if the issue is not resolved, let me know if this is a built-in microphone or an external one that is causing the issue.
Regardless, I do believe you can resolve the issue with these troubleshooting steps. Either way, please let me know. Thank you for posting on the HP Forums. Have a great day!
Mario