no sound

What kind of sound card do you have? Which version of Ubuntu? Have you tried adjusting all you can in the Volume Control (right-click on the volume icon)?

Can you provide the output of this commands:

sudo lspci
amixer scontrols
amixer sget 'Master'
amixer sget 'PCM'

Thanks

This is another user : Soori facing similar problem

sudo lspci
0000:00:00.0 Host bridge: Intel Corporation Mobile 915GM/PM/GMS/910GML
Express P rocessor to DRAM Controller (rev 04)
0000:00:02.0 VGA compatible controller: Intel Corporation Mobile
915GM/GMS/910GM L Express Graphics Controller (rev 04)
0000:00:02.1 Display controller: Intel Corporation Mobile
915GM/GMS/910GML Expre ss Graphics Controller (rev 04)
0000:00:1c.0 PCI bridge: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6
Family) P CI Express Port 1 (rev 04)
0000:00:1d.0 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW
(ICH6 Famil y) USB UHCI #1 (rev 04)
0000:00:1d.1 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW
(ICH6 Famil y) USB UHCI #2 (rev 04)
0000:00:1d.2 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW
(ICH6 Famil y) USB UHCI #3 (rev 04)
0000:00:1d.7 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW
(ICH6 Famil y) USB2 EHCI Controller (rev 04)
0000:00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev
d4)
0000:00:1e.2 Multimedia audio controller: Intel Corporation
82801FB/FBM/FR/FW/FR W (ICH6 Family) AC'97 Audio Controller (rev 04)
0000:00:1e.3 Modem: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6
Family) AC'97 Modem Controller (rev 04)
0000:00:1f.0 ISA bridge: Intel Corporation 82801FBM (ICH6M) LPC
Interface Bridge (rev 04)
0000:00:1f.1 IDE interface: Intel Corporation 82801FB/FBM/FR/FW/FRW
(ICH6 Family ) IDE Controller (rev 04)
0000:00:1f.3 SMBus: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6
Family) SMBus Controller (rev 04)
0000:03:03.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
RTL-8139/8139C /8139C+ (rev 10)
0000:03:05.0 CardBus bridge: O2 Micro, Inc. OZ711MP1/MS1 MemoryCardBus
Controlle r (rev 21)
0000:03:05.2 0805: O2 Micro, Inc.: Unknown device 7120 (rev 01)
0000:03:05.3 Bridge: O2 Micro, Inc.: Unknown device 7130 (rev 01)
0000:03:05.4 FireWire (IEEE 1394): O2 Micro, Inc.: Unknown device 00f7
(rev 02)
0000:03:09.0 Network controller: RaLink: Unknown device 0302
soori@soori-laptop:~$ amixer scontrols
Simple mixer control 'Master',0
Simple mixer control 'Master Mono',0
Simple mixer control 'PCM',0
Simple mixer control 'Surround',0
Simple mixer control 'Surround Jack Mode',0
Simple mixer control 'Center',0
Simple mixer control 'LFE',0
Simple mixer control 'Line',0
Simple mixer control 'CD',0
Simple mixer control 'Mic',0
Simple mixer control 'Mic Boost (+20dB)',0
Simple mixer control 'Mic Select',0
Simple mixer control 'Video',0
Simple mixer control 'Phone',0
Simple mixer control 'IEC958',0
Simple mixer control 'IEC958 Playback AC97-SPSA',0
Simple mixer control 'PC Speaker',0
Simple mixer control 'Aux',0
Simple mixer control 'Mono Output Select',0
Simple mixer control 'Capture',0
Simple mixer control 'Mix',0
Simple mixer control 'Mix Mono',0
Simple mixer control 'Channel Mode',0
Simple mixer control 'Duplicate Front',0
Simple mixer control 'External Amplifier',0
soori@soori-laptop:~$ amixer sget 'Master'
Simple mixer control 'Master',0
  Capabilities: pvolume pswitch pswitch-joined
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 31
  Mono:
  Front Left: Playback 31 [100%] [on]
  Front Right: Playback 31 [100%] [on]
soori@soori-laptop:~$ amixer sget 'PCM'
Simple mixer control 'PCM',0
  Capabilities: pvolume pswitch pswitch-joined
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 31
  Mono:
  Front Left: Playback 25 [81%] [on]
  Front Right: Playback 25 [81%

Soori, your mixer settings seems to be fine. Still, try to run "alsamixer" and adjust all levels and mute/unmute channels.

The newest intel sound chips are problematic, try google around for snd-hda-intel and ubuntu.

https://help.ubuntu.com/community/HdaIntelSoundHowto
http://www.alsa-project.org/alsa-doc/doc-php/template.php?company=Intel&card=ICH+southbridge+HD-audio+and+modem.&chip=ICH6%2C+ICH6M%2C+ICH7%2C+ESB2&module=hda-intel#opt
https://launchpad.net/distros/ubuntu/+source/alsa-driver/+bugs

Posting this in case it helps anybody.

Sound worked for me in Ubuntu Breezy, but in a completely new install of Dapper - no sound at all.
I see many people all over the place struggling with this. After many hours of googling, I found a simple workaround which works for me. It was described on: https://bugtrack.alsa-project.org/alsa-bug/view.php?id=2038

So basically what I did (as root or using sudo):
1) Add to the bottom of /etc/modprobe.d/alsa-base: options snd-hda-intel model=ref
2) Reboot

Voila! Sound works.

My system:

Dell Dimension 9150

OS: Ubuntu Dapper (6.06 LTS)

cat /proc/asound/version:
Advanced Linux Sound Architecture Driver Version 1.0.10rc3 (Mon Nov 07 13:30:21 2005 UTC).

lspci -vv | fgrep Audio:
0000:00:1b.0 0403: Intel Corporation 82801G (ICH7 Family) High Definition Audio Controller (rev 01)

cat /proc/asound/card0/codec#0:
Codec: SigmaTel STAC9221 A1

aplay -l:
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 1: STAC92xx Digital [STAC92xx Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Note that this fix *doesn't* work on my system (Gateway MX3410), but that I've heard success stories from quite a few others with it.