I use a Dell Inspiron N7110 Laptop and had no problem using a HDMI cable to send what was on my laptop display to my TV. Video and Sound were working fine.

But now I'm only getting the video signal... No sound?

You need to check that the audio processor on the Video card is enabled. To get sound from the HDMI port you need this option.

Right-click the volume control icon on the bottom taskbar and click on "Playback Devices" to open the pop-up window for sound options.

In the "Playback" tab, select "Digital Output Device" or "HDMI" as the default device, click "Set Default" and click "OK" to save the changes. This method works with a straight HDMI-to-HDMI connection

Thanks to xpcman for this tip.