I know this is a easy problem to fix normally, but I've had no success yet. I have a Sony Vaio FW with Windows Vista, and a Maxent TV. I've connected the laptop to the tv with an HDMI cable. The image is displayed on the tv with no problem but there is no sound whatsoever. I've gone to the control panel and changed the default sound device to HDMI Device, still no success. I went into "Configure" and pressed on "Test", and it says it failed.
I've also noticed that when I play a movie or anything at all with sound, the computer itself doesn't register the sound, because I click the sound icon in the bottom right corner, and normally there's a green bar that moves up and down according to the volume of the sound currently playing, but when it's set to HDMI there's nothing at all.
Any help would be appreciated.

You may need to change settings in the TV software. Do you hear system soulds through the TV when the HDMI is attached?

No, I don't hear anything at all. I take it I'd need to change the sound settings on the TV, but what exactly would I need to change?
Thank you for replying, by the way. :-)

Your sound card has to pass the sound output to the HDMI, so I would guess that that HDMI would be under output devices for your sound card. The best approach would be to update the sound and video drivers from the manufactures website. If you don't find a solution there, you could just pick up an audio cable.