Even if it is, please verify all of the following;
Open Control Panel - Sounds and Audio Devices. On the Volume tab, ensure Mute is not checked.
Click the Audio tab. Is your sound device listed in the Sound playback box?
Click the Voice tab. Is your sound device listed in the Voice playback box?
Go back to the Volume tab. Under Device volume click on Advanced. In the Play Control window that opens, click Options in the menu bar. Click Properties. Is your sound device listed under Mixer device?
In the lower half of the window,
put a check mark in Auxiliary, and any other boxes which may be connected/associated with your video player.