First determine if the sound card is on board or if it is a PCI or ISA.
If it is an onboard sound chip check in the system bios and see if it enabled.
Next thing to do is check the driver state, right click on My Computer and select properties, Then click on the Device Manager tab and look at sound and video game controllers.
If you see a device with a red yellow marker click on the device and click the properties button this will bring up a window that tells you some information like windows was not able to allocate resorces for this device etc.
It may be that another device has grabbed the IRQ or I/O that the sound card needs and is not releasing it, which in this case you may have to allocate resorces in the system bios for the particular slot the soundcard is in or turn on the plug and play OS feature in the bios to allow windows to reallocate resorces asigned by the bios.
as a last resort you may have to remove the conflicting devices from device manager and reboot the system allowing windows to redetect the devices and reinstall the drivers.
Before doing this it is a good idea to have the device drivers and the windows cd ready when they are asked for.
Post you results and let us know how you made out.
