I just purchased a used Compaq Evo N600c running Windows XP Home SP2 with an ESS allegro PCI sound card. The Laptop also has a built-in microphone. When I play sounds they seem to be working but no sound comes out of the laptop. But my microphone works. Even when I test the hardware in Device Manager the results are "your hardware is working properly" all drivers show working. When I used the sound up/down button on the laptop it would show a visual sound bar on-screen. When I tried to go to volume CONTROL I realized it wasn't there. So I downloaded it. Now when I use the volume button on the laptop no visual sound bar, but it shows volume moving in sound control. I have tried every combination of updating, rolling back, uninstalling, re-installing and downloading from manufacturer page. When I put headphones in they do work. I have run out of IDEAS. It is probably not a hardware issue because earphones and microphone still work. And it's not a driver issue because I have done EVERYTHING! There are no hardware conflicts and volume is at a good level. Can anyone help me?

System Info:
Win XP Home SP2
Compaq evo N600c
ESS Allegro PCI Audio (WDM)Is this your first Compaq?  Is it an old model?
Look around. Look at all the buttons. Turn it over. There is another place where you can shut off the speakers. 
NO? OK, then the headphone jack is out of shape. It shuts off the speakers when you insert a headphone. A tech will have to take a look at it and see if that is the problem and if can be fixed without tearing up the whole thing!  Quote

There is another place where you can shut off the speakers.

when I use the volume button on the laptop no visual sound bar, but it shows volume moving in sound control.