No audio output device installed in p6507c

I did a system reinstall of Windows 7 when I first discovered this problem and was successful in going back to all original settings. However I am still seeing a red X on my speaker icon. As a computer user I am best described as a novice, if you know how to fix this issue for the model number of the computer that I have (p6507c desktop HP) please provide as much detail as possible and a link to where I can find the proper audio device for my desktop.

Thank You.