The issue this fix addresses was on an HP Compaq 515 running Windows 7 Home Premium.
-Computer is a laptop with working speakers
-When headphones are plugged in they are detected but do not play music
-You cannot set the headphones as the default playback device even if you disable the speakers
-Reinstalling the audio drivers does NOT work
You could apply this method (basically of making Windows use default drivers) to similar audio issues, ie I have done this with a computer with Realtek audio as well (although the original problem was totally different)