sound - only dummy output in ubuntu 20.04

I have no sound in my ubuntu 20.04
I have tried a lot of things, but with no success. Audio only works with headphones.
could someone help please...

$ pacmd list cards | egrep -i "output|active"
 argument: <sink_name=auto_null sink_properties='device.description="Dummy Output"'>
  device.description = "Dummy Output"
  device.description = "Monitor of Dummy Output"
0 source output(s) available.

$ sudo lspci -vv | grep -i audio
00:1f.3 Audio device: Intel Corporation Device 51c8 (rev 01) (prog-if 80)

ALSA Information Script v 0.4.64
--------------------------------

This script visits the following commands/files to collect diagnostic
information about your ALSA installation and sound related hardware.

  dmesg
  lspci
  aplay
  amixer
  alsactl
  /proc/asound/
  /sys/class/sound/
  ~/.asoundrc (etc.)

See '/usr/sbin/alsa-info --help' for command line options.

alsactl: save_state:1595: No soundcards found...
cat: /tmp/alsa-info.1fq2MBPWfF/alsactl.tmp: No such file or directory
Automatically upload ALSA information to www.alsa-project.org? [y/N] : y
Uploading information to www.alsa-project.org ... Done!

Your ALSA information is located at http://alsa-project.org/db/?f=2cab8ba99bc9766f7a58b46c9725aeb87e9721d1