I'm sorry to hear that you're having this issue.
If no HDMI cable seems to work, and by your post it appears that you have tried several, I would recommend having the unit serviced.
One thing you can try is, with the TV powered ON, press and hold the EXIT button to reset the TV. (All of your settings will be reset as well, including picture and audio). Then turn the TV off, and plug your devices back in to see if that helps.
If not, your unit may require service.
I have a Samsung Plasma PS50c6900 TV and the Samsung Home Theater HT-C6930w. Until now I had both of them connected with the HDMI cable.
SInce I had to move the HT to another position I unplug the HDMI and I connect it again later. Teh connection of the HDMI was done with both equipment unpluged from the electricity power.
After that I do not have picture from the HT to my TV and a message that there is no video signal, check the cables is coming to my TV. Also the Anynet+ is not recognizing my HT.
The TV recognize that the HDMI cable is connected.
I use other HDMI cables with no result.
I try to connect the HT to another TV with the HDMI but no video signal is coming.
What may be the problem? Please help!