I had a problem like this a while ago, I had sound from my speakers but not headphones, what I found worked is to turn off "Jack detection" by doing this it worked,
If you tried that and it did not work then apologies, just thought Id mention it.
Try these drivers, they work much better than the official pcs on my defiance Vii 15"
GitHub - AlanFinotty/AAFDCHDriverMod: Realtek Audio Driver Mods by Alan Finotty
Realtek Audio Driver Mods by Alan Finotty. Contribute to AlanFinotty/AAFDCHDriverMod development by creating an account on GitHub.github.com