HDMI sound missing

So far I've managed to screw the HDMI sound option from the volume menu and the sound control panel. I was trying to switch between to the motherboard sound option from the GPU card HDMI sound option and clicked on disable on the mixer panel from the sound control task-bar.

Should I just re install the HDMI sound drivers from the GPU?

Thanks for ur help :)

I re-installed the GPU drivers from AMD which included the audio drivers for the add on video card. The sound works ok now. However, still cant switch from on board sound from the motherboard to the HDMI sound on the video card. In Win7 I use the Smart Audio application to choose which one I want active.

(The on board sound card is hooked up to a stereo amplifier, the HDMI sound is hooked up to PC speakers)