And here is a trick how to awoid traps from Your OS and to know did Your hardware work.
Please , download and burn as ISO file , ubuntu linux LIVE CD . Compleete procedure and download link You have here -
https://help.ubuntu.com/community/LiveCD
Choose 12.04 (never mind the 32 or 64 bits).
Boot it (be sure that You set cd-dvd as a first boot option in bios) .
This is a OS that run from CD , no need to instal.
After boot , put a usb stick with one (or more) song , double click and if You can hear the sound , everything is OK with Your speakers.
You can allways backup Your personal files and did a OS recovery to set Your original hardware factory settings.
If the hardware works , that will for sure solve Your problem.
Wish You good luck and all the best!!!