Try this...
1. Go to "Control Panel" and then to "Sound".
2. In here click (once only) on the listing for your speakers and then click the "Properties" button at the bottom of the window.
3. Next click on the the "Levels" tab and change the levels to be what works for you. Personally I tend to set the ones relating to the speaker (not the mic, line in, etc.) to 100 and then when you want to raise or lower the sounds, you can do it just from the main speaker access.
4. Once you have changed the settings to where you want them, click "Apply" and then click "OK".
Close the windows that were opened and you should be good.