Sony Vaio HDMI sound from laptop not tv

Hello,
I have a Sony Vaio 17 inch full HDMI laptop using Vista. I have been using a HDMI cable connected to my TV for a few months now all working fine yet today for no apparent reason the sound has started coming through my laptop rather than the TV. I have gone to the control panel and tried switching the default sound to the realtec digital however this did not work and I ended up with no sound at all. Any ideas how to fix this? I have tried two different players both VLC and Zoom player.

Regards

Sylver