A system at the office was having the Realtek audio control panel icon showing up in the system tray, with the 3d test working, but windows wasn’t showing the audio device in the sound and audio control panel applet. Instead windows said that not audio playback device was found. As a result no applications were able to play audio.
This post at tomshardware.com provided an easy solution.
Just open regedit and delete the key folder //HKEY_LOCAL_MACHINE/SYSTEM/CONTROLSET001/ENUM/HDAUDIO and restart your computer. It should prompt you to install the hardware again.
That fixed the hardware issue and the user was able to view www.abcnews.go.com/whatwouldyoudo happily.