We're all on your side, TinglyCourier !
I learned from your introduction that you are experienced with those things and you might know more about that stuff than me - I hope you don't mind if I ask some things anyway:
A: What exact model is the audio chip? ALCx50? RTL...? Which driver package did you try? How did you check which chip you have? Tool? (They fail sometimes with audio chips) Eyes?
B: What is the exact make and model of the computer? If homebuild or rather unknown brand, what is the manufacturer and model of the mainboard?
You say you've tried almost anything. Even if your kids just tied you feet up to the ceiling lamp, try to describe what you've tried. This might help us helping you. Installing onboard sound is hell sometimes.