after the last update, and restart, the sound didn't work anymore

output from 'uname -a':
Linux poseidon 3.19.0-18-generic #18-Ubuntu SMP Tue May 19 18:31:35 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: alsa-base 1.0.25+dfsg-0ubuntu4
ProcVersionSignature: Ubuntu 3.19.0-18.18-generic 3.19.6
Uname: Linux 3.19.0-18-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: michel 1967 F.... pulseaudio
CurrentDesktop: GNOME
Date: Sat May 23 08:54:23 2015
InstallationDate: Installed on 2014-10-18 (216 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
PackageArchitecture: all
SourcePackage: alsa-driver
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:PCH failed
Symptom_Card: Intern geluid - HDA Intel PCH
Symptom_DevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: michel 1967 F.... pulseaudio
Symptom_Jack: Green SPDIF Out, Rear
Symptom_Type: No sound at all
Title: [MS-7823, Realtek ALC892, Green SPDIF Out, Rear] No sound at all
UpgradeStatus: Upgraded to vivid on 2015-04-27 (25 days ago)
dmi.bios.date: 06/07/2013
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: V1.2
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: H87M-G43 (MS-7823)
dmi.board.vendor: MSI
dmi.board.version: 1.0
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: MSI
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrV1.2:bd06/07/2013:svnMSI:pnMS-7823:pvr1.0:rvnMSI:rnH87M-G43(MS-7823):rvr1.0:cvnMSI:ct3:cvr1.0:
dmi.product.name: MS-7823
dmi.product.version: 1.0
dmi.sys.vendor: MSI