There are a few things you can check to diagnose this problem:

1. Is the player volume low or muted? Hover the mouse pointer over the boom box icon to change the volume level, and click it to toggle muting.

2. Is the system volume low or muted? In Windows, check this by clicking on the speaker icon in your system tray.

3. Are your speakers or headphones plugged in? Check any volume settings on those.

If none of these suggestions help, let us know.