Make sure that a sound device is installed on your computer; if one isn't, just install one. In most cases, Windows will automatically detect the new hardware and install the necessary software drivers. If Windows does not automatically install the software drivers, run the Add Hardware Wizard to install them yourself (click Start, click Control Panel, and then double-click Add Hardware).

Another program is using the sound device, and preventing the Player from accessing it. Close all other programs so that the Player is the only program running, and then try to play the file again.

The software drivers for your sound device may be missing or corrupted. Try reinstalling the most recent software drivers for your sound device by scanning for updates on the Windows Update Web site or by going to your sound device manufacturer's Web site.

The Player may be using a version of Microsoft DirectX that is incompatible with the hardware features on your sound device. (This may explain why you can hear sound when you use some software programs, but not when you use the Player.) Install the most current version of DirectX by going to the DirectX Web page.