Go to Control Panel -> Sounds and Audio Devices then click the Audio tab. Try selecting different options from the Default Device drop down list, remembering to click Apply each time before testing.

If that doesn't work there are lots of other options on the Sounds and Audio Devices screen to try if you haven't already done so. Be sure to check all the volumes.

Go to Control Panel -> Sounds and Audio Devices then click the Audio tab. Try selecting different options from the Default Device drop down list within the sound playback section, remembering to click Apply each time before testing.

If that doesn't work there are lots of other options on the Sounds and Audio Devices screen to try if you haven't already done so. Be sure to check all the volumes.