yeah the best thing to do buddy is open audacity then go to:
Control panel > Sound Speach And Other Sound Devices > Sound And Audio Devices > Advanced > Properties > (Change Mixer Device To Sound Input or Similar but not mic)
then hit record on audacity and play a tune, adjust the volumes that come up when you changed mixer device to input and adjust the "Stereo Mixer" volume bar until it shows recording volumes, adjust it to your level and click apply but make sure you dont have it at full else it will be distorted.
it does this with me sometimes too because the volume on the stereo mixer goes right down to 0 for some odd reason, probably restarting pc or something, but give that a shot, tell us if it works
