Most sound card problems are a result of improper, defective, or misconnected cables, incorrect drivers, or resource conflicts. Sound card problems that occur with a previously functioning sound card when you have made no changes to the system are usually caused by cable problems or operator error (such as accidentally turning the volume control down). Sound card problems that occur when you install a new sound card (or when you add or reconfigure other system components) are usually caused by resource conflicts or driver problems. Resource conflicts, although relatively rare under Windows 9X/2000/XP in a PCI/PnP environment, are quite common on machines running Windows NT and/or ISA, because sound cards are resource hogs.
To troubleshoot sound problems, always begin with the following steps:
Verify that all cables are connected, that the speakers have power and are switched on, that the volume control is set to an audible level, and so on. In particular, if the sound card has a volume wheel on the back, make sure it is set to an audible level. It’s often unclear which direction increases volume, so we generally set the wheel to a middle position while troubleshooting.
Shut down and restart the system. Surprisingly often, this solves the problem.
Determine the scope of the problem. If the problem occurs with only one program, visit the web sites for Microsoft, the software company, and the sound card maker to determine if there is a known problem ...