You will have to check for the correct driver installation related to the soundcard installed in your computer. To do this, go to Start > Run > devmgmt.msc. Locate the device under the Audio Devices and make sure it's installed properly. Then go to System Tray, double click the C-Media icon, and make sure it's configured properly in terms of jack input. Double click the colored inputs and assign the correct jacks and it should work.
