If you got the driver CD then just install the sound drivers.

You can also check the drivers from device manager. Check whether drivers are properly installed or not. if it's not then, you will have a option "update drivers" just click that and follow the instructions. 

Make sure to check you volume icon in task bar.

If you don't have drivers on CD, then go to google and find drivers.

Whenever you have a problem with your PC, make sure to mention about the Operating System.  

Hope it helps