|See Response 6 in this|
" Make sure you don't have volumes set too low or muted, for things you want to hear or use.... "
Note that the sound is Muted if the blue speaker icon has a red circle icon with a diagonal bar.
SOME sound adapters may also have a feature where you can boost the sound in there somewhere..
Other than that, you can't increase the sound levels (volumes) with any software - it's a hardware limitation - get yourself some better amplified speakers, and/ or a better sound adapter card you install in a mboard slot if you have a desktop computer, if you need to.