Some of this may be obvious but, it may be a place to start for you
Check volume settings:
Often no sound in the Microsoft Windows Media Player is corrected by adjusting the volume controls at the bottom of the window. Moving the slider from the left to the right will turn up the volume, if all the way to the left the volume is turned all the way down.
Make sure not muted:
In addition to the volume slider, make sure the sound icon is not pressed in. This button is the mute button and will mute the sound.
Make sure the Equalizer is balanced:
If the equalizer is all turned down you may experience sound related issues. To check this setting, click View, Enhancements, Graphic Equalizer. Once the Graphic Equalizer is displayed, make sure all settings are at least mid way.
Sound settings:
Verify your sound settings are correct. When other software programs are installed it's possible for the programs to incorrectly adjust your sound settings causing issues with your sound. Additional information about troubleshooting your sound card in Microsoft Windows can be found on document CH000208.
Update / Reinstall the Windows Media Player
If you continue to experience issues, you may want to consider reinstalling and/or updating the Windows Media player on your computer. You can find the latest Windows Media player on your computer by clicking here