No sound from HDMI

Hi

I have a XPS17

win 7 64 bit

Nvidia Gforce GT 555M

When I got the laptop, I was able to plug my laptop to my LG tv via HDMI, sound and image was working find

A few months ago, my hard drive die and I replace it. Reinstall Win 7 64 bit and all the recommanded driver (from dell.ca web site)

since then I have NO sound on my TV, image perfect.

I tried everything, uninstalling and reinstalling driver, diagnostic tools from dell, went to a search on this issue on the dell web site and google search, tried all the fix....same issue

any idies???

thanks