Right click on speaker icon on the bottom right hand corner of your screen, select "playback devices"
Select something like HDTV or HDMI or something like that, right click it and select "Set as default device" See if it works
Also, make sure the volume on the TV is turned up! Get the remote control, press the Volume UP button, there should be something like "Volume" and a bar that fills up or a number that goes up. ALso make sure the mute is not activated, so press "mute" and see if an icon that looks like a speaker with a line through it appears, then press it again until it disappears so that you are sure that it is not on mute