Well, that can be a couple of different things.
- Check your audio settings. Double click on the speaker icon in your system tray to open the Master Volume control (Windows). Make sure that neither the “Master Volume” or “Wave” isn’t too low or muted.
- If that looks good, follow this link to check to check the version of flash you have installed: http://www.adobe.com/products/flash/about/. You’ll need version 9.0 or higher.