Ubuntu 9.04 Jaunty — Headphone jack not working problem Solved
After the installation of ubuntu 9.04 , I found that my laptop speakers were working fine but headphone jack was not working. Some bit of googling and I stumbled upon a solution to the problem .
You have to append the following two lines to file /etc/modprobe.d/alsa-base.conf
//add this lines
options snd-hda-intel model=3stack enable=yes
options snd-hda-intel model=auto position_fix=1 enable=yes
and restart laptop.
Hope it will fix the problem. My laptop was hp pavilion dv2000 series.