What other things have you tried? Have you tried hitting up the sound icon in the control panel and checking out the settings? Do you have your microphone connected and is it running as well at the same time you are trying to say listen to music because it could be that if your mic is one for some reason, there is a setting in windows that will lower the audio volume to allow for clearer conversations through the microphone.
Is there a realtek audio control panel? Have you tried playing around with the settings in there? Let me know if that idd not help at all and I will try again