Speakers don't work but headfones do

My laptop speakers do not function as they should when i installed ubuntu 12.04. But when i plugged in headfone, it worked fine. This problem started only when i installed Ubuntu 12.04 and before it was working fine.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: alsa-base 1.0.25+dfsg-0ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-26.41-generic 3.2.19
Uname: Linux 3.2.0-26-generic x86_64
NonfreeKernelModules: wl
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
AplayDevices:
 **** List of PLAYBACK Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: HDA Generic [HDA Generic]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
ApportVersion: 2.0.1-0ubuntu8
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: HDA Generic [HDA Generic]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: kartikeya 1697 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xfe9fc000 irq 45'
   Mixer name : 'SigmaTel ID 7616'
   Components : 'HDA:14f12c06,14f1000f,00100000 HDA:10951392,10280242,00100000 HDA:83847616,10280242,00100201'
   Controls : 4
   Simple ctrls : 3
Date: Thu Jul 12 16:22:05 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_IN:en
 PATH=(custom, no user)
 LANG=en_IN
 SHELL=/bin/bash
SourcePackage: alsa-driver
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:Intel failed
Symptom_Card: Built-in Audio - HDA Intel
Symptom_DevicesInUse:
 1697/dev/snd/controlC0: kartikeya F.... pulseaudio
 ND
Symptom_Jack: Digital Out, HDMI
Symptom_Type: No sound at all
Title: [Inspiron 1525, Silicon Image ID 1392, Digital Out, HDMI] No sound at all
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/27/2008
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A13
dmi.board.name: 0U990C
dmi.board.vendor: Dell Inc.
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA13:bd06/27/2008:svnDellInc.:pnInspiron1525:pvr:rvnDellInc.:rn0U990C:rvr:cvnDellInc.:ct8:cvr:
dmi.product.name: Inspiron 1525
dmi.sys.vendor: Dell Inc.
mtime.conffile..etc.modprobe.d.alsa.base.conf: 2012-06-02T14:33:32.945880