Hi MindyB,
1. Was it working fine before?
Please check the link below to update the audio Codec.
Check for the issue after installing the audio codec.
It's possible that you have RCA (red/white) jacks that indicate Audio Out by your TV card and you will want to connect that to the Audio In for the TV. Make sure that you connect it to the same as the HDMI (ie. Video 1, Video 2, DVI, etc.)
Please Post back and let us know if this has helped to resolve your issue.
Regards,
KarthiK TP