Based on the information that you have provided we would suggest double checking all your HDMI cables and connections. Make sure that you do not have any bent or damaged cables and/or connections. And check this on all cable ends and connections on all components. Just one bent or missing pin can cause a loss in picture and/or sound.
Checking the audio and/or video settings of the connected source or component is also suggested. Often times there are settings that you can adjust to either enable or disable audio and video output through HDMI.
Also consider your overall cable length and try to use the shortest HDMI cables possible for your system.