Hello my friend, i had encounter same problem as you have when i on one of my client's computer. You can reinstall the driver of your sound card. When you installed the program driver of your cam the sound card is affected due to some factor either the sound card is currupted. So my solution are the following:
1. Go to my computer icon then right click it the click properties. Then go to Tab name Hardware then click device manger then check if the sound driver is not installed or it is being corrupt. Then proceed to the reinstallation of your sound card driver. But if the sound card driver is installed then reinstall you windows media player. If you don't have installer then try this link: http://www.microsoft.com/windows/windowsmedia/player/10/default.aspx
2. Donwload Windows media player codec and update the codec of your Windows Media Player. try this link: http://www.microsoft.com/downloads/details.aspx?familyid=06fcaab7-dcc9-466b-b0c4-04db144bb601&displaylang=en
Hope this help fix your problem. If you need more help just contact me or reply to this post.