First check Windows audio is running in services. Go to run and type services.msc. In the window that opens, scroll down to Windows Audio and double left click. Check that it is running and on auto. Click apply and OK if you have to change anything. Close the window.

Now right click the Speaker icon in the notification area (bottom right) and select Playback Devices. In the window that opens, right click a blank space and tick the boxes for Show Disabled Devices and Show disconnected devices.

In the list do you see your speakers? They should show as ready. You can right click and in the menu select as default. In the same menu you can also test any device for sound as long as it's the default.

See if that helps.

Worth checking that the speaker jack is connected to the green socket at the back.

Go to run again and type devmgmt.msc, in device manager expand sounds, video and games controllers, any yellow warnings?

Try going back to Playback Devices and disable the Digital Output Device, apply OK. Open playback devices again and see if your speakers are now 'ready' and can be set as default. I assume Windows audio is OK?

OK. Go back to device manager, sound,video and game controllers and right click the entries, properties, then the detail tab, device description, and scroll down to manufacturer. See if you can find out if you have a Realtek chip. If no information then download free SIW and check under audio what type of chip it is, http://download.cnet.com/SIW-Portable/3000-2094_4-75449686.html