This may be caused from several reasons.
1, Run the command "sndvol32.exe /r" from your computer's "Start -> Run ..." . Then the recording control panel window will appear, make sure
* check the right device, most situations you should check the "Stereo Mixer" device, if you record from microphone, then you should check the "Mic" device.
* Uncheck the "mute"
* Set the volume to a higher value2, If the above step does not help,
please launch your computer's control panel from "start -> settings -> control panel", then double click the item "Sounds and Multimedia", adjust the hardware accelaration to none. Do not use the hardware accelaration feature. And try it again. 3, It the above steps still do not help,
besides the above settings, your media player or other applications may also have hardware acceleration options. Make sure to set the player's or other application's hardware acceleration property to none too. | 
