Alternate fix, if you have no open mic jacks, as my motherboard has 3 jacks, which I have reassigned to become 5.1 sound jacks , (mic in for sub, line in for side).
Go to control panel, sound, recording tab. Right click in the middle and select show disabled connections. You should see an option labeled "Stereo Mix". If it's disabled, enable it. If it's enabled, disable it.