No sound

Hi,
I'm having a problem and I need some help. I connect my computer to my TV with a HDMI cable. It has worked fine for a long time. However, now when I connect it the sound does not transfer to the TV. It continues to come from the computer. I also have another issue which may be related. On the right side of the task bar the icon for MouseKeys has gone black and nothing happens when I click on it with either a left or right click. I think both these things happened at the same time but I'm not sure. I have a Dell Latitude computer running Windows 7. Any help would be greatly appreciated.
Thanks,
Steve

hover over the speaker icon of the bottom right, right mouse click and go to playback devices. look for HDMI AUDIO, double click on it, and check the levels. Also check that there's nothing muted.

Hi,

Can you work your laptop if you were to disconnect the HDMI lead temporarily from the TV?

Does the problem replicate when laptop disconnected from TV?

To behutchins advice. I did that and couldn't find either HDMI or audio there. I did look all around when there.

To iko22s advice. Everything works fine in with either the cable connected or disconnected except the volume on the TV.

Thanks to both for your advice. Any other ideas?