Have you got the `Volume` turned down? There is a volume icon either in the Taskbar on the right hand side or in Sounds and Audio Devices Properties/Volume tab make sure the `Place volume icon on the taskbar` box is ticked.
Left clicking the volume icon in the Taskbar will bring up the volume control or you can adjust it in Sounds and Audio Devices. If you Right click the icon or click Advanced in Sounds and Audio Devices you will get another window make sure all volumes are full and none have the Mute box ticked.
You can also go to `Options/Properties` in the Master Volume window and make sure all boxes are ticked for `Playback` and the other buttons.
If you have a volume control between the external speakers and the PC make sure that is turned up as well.
Let us know how you get on.