My Toshiba laptop's sound just turned off and it won't come back on? How do I get it to come back?

I tried hitting the little sound icon on the "start" toolbar on the bottom with both the left and right mouse buttons but all it says is there is no audio output device installed.
I tried turning up the sound, but nothing happened.
The sound icon is a little speaker, and it usually has little lines indicating the sound level, but now it just has a red "x" over it.
How do I get my sound back?
I'm using Windows Vista.

Still having the speaker with the red x would lead me to believe you have checked the mute box. Have you checked on the mixer to see if this has been accidentally selected? Right click on the speaker icon and select Mixer. The check box is at the bottom of the speakers/volume bar.

If this is NOT the problem, then go to the device manager and delete the sound card. Reboot the machine and allow it to reload the sound drivers. This should put you back in operation.