Hi Freddy,
I assume you've checked in device manager (right click 'my computer' - manage- select device manager) to see if there are any unknown or uninstalled devices (usually shown with a exclamation mark in a yellow circle.
If you are certain it's a hardware fault then (someone correct me if I'm wrong here) I think you'll find that the sound module is built in to the motherboard so can't be removed, if however it can I'll give you a bit of a start on how to take it apart, but I don't have one infront of me so this will only be the first few steps...
1. Remove the battery (and make sure it's unplugged from the mains)
2. Remove the screws underneath marked 'k' (this is for keyboard)
3. using a flat blunt object gently lift & remove the plastic cover with the power button on.
After this I can't remember how many additional screws there are for the keyboard etc but you should start to be able to see what goes where and how it comes apart.