Sound problem after changing the desktop enviroment to KDE Plasma

[Abulfazl Haidary]

after installing Ubuntu 20.04 and changing its desktop environment from its default to KDE Plasma my sound card stopped from begin working, although I did some modifications bu it didn't work.
my system info is:
Card: HDA Interl PCH
Chip: Realtek ALC3235

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: alsa-base 1.0.25+dfsg-0ubuntu5
ProcVersionSignature: Ubuntu 5.11.0-43.47~20.04.2-generic 5.11.22
Uname: Linux 5.11.0-43-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.21
Architecture: amd64
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/controlC0', '/dev/snd/hwC0D2', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D10p', '/dev/snd/pcmC0D9p', '/dev/snd/pcmC0D8p', '/dev/snd/pcmC0D7p', '/dev/snd/pcmC0D3p', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Mon Dec 20 10:55:08 2021
InstallationDate: Installed on 2021-12-07 (12 days ago)
InstallationMedia: Ubuntu 20.04.3 LTS "Focal Fossa" - Release amd64 (20210819)
PackageArchitecture: all
SourcePackage: alsa-driver
Symptom: audio
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/09/2016
dmi.bios.release: 1.11
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.11.3
dmi.board.name: 0T6HHJ
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.11.3:bd11/09/2016:br1.11:svnDellInc.:pnLatitudeE7470:pvr:sku06DC:rvnDellInc.:rn0T6HHJ:rvrA00:cvnDellInc.:ct9:cvr:
dmi.product.family: Latitude
dmi.product.name: Latitude E7470
dmi.product.sku: 06DC
dmi.sys.vendor: Dell Inc.
mtime.conffile..etc.modprobe.d.alsa-base.conf: 2021-12-14T11:09:06.124726