Loss of Sound in a Debian Jessie system

Can anyone please help with a problem concerning the loss of sound in a Debian Jessie system. N.B. The person must be in the UK as phone support is required. Due to sound problems whereby sound was first okay, then lost, then regained, then lost again when running vlc on a sound file and also when running YouTube, the following was done :- Pulseaudio was installed on Friday and % dpkg -l | grep pulseaudio gave ii pulseaudio 5.0-13 amd64 PulseAudio sound server ii pulseaudio-module-x11 5.0-13 amd64 X11 module for PulseAudio sound server ii pulseaudio-utils 5.0-13 amd64 Command line tools for the PulseAudio sound server % aplay -l gave **** List of PLAYBACK Hardware Devices **** card 0: PCH [HDA Intel PCH], device 0: ALC887-VD Analog [ALC887-VD Analog] Subdevices: 0/1 Subdevice #0: subdevice #0 card 0: PCH [HDA Intel PCH], device 1: ALC887-VD Digital [ALC887-VD Digital] Subdevices: 1/1 Subdevice #0: subdevice #0 card 1: NVidia [HDA NVidia], device 3: HDMI 0 [HDMI 0] Subdevices: 1/1 Subdevice #0: subdevice #0 card 1: NVidia [HDA NVidia], device 7: HDMI 1 [HDMI 1] Subdevices: 1/1 Subdevice #0: subdevice #0 Jessie was then re-booted and the sound then re-appeared. Also % ls /etc/pulse gave [login to view URL] [login to view URL] [login to view URL] [login to view URL] and % ls ~/.pulse gave [login to view URL] [login to view URL] 259df95a2b75426bb6ef25f372b08be2-runtime@ [login to view URL] [login to view URL] 3e0b1f6422592f67f9f012034c3323d0-default-sink 3e0b1f6422592f67f9f012034c3323d0-default-source [login to view URL] 3e0b1f6422592f67f9f012034c3323d0-runtime@ [login to view URL] Vlc was used to run a test sound file ([login to view URL]) and that ran okay. Sound also worked fine on YouTube. However, the sound was then lost when trying to use vlc again on a sound file and also was not present when trying to use sound with a Web browser. % vlc [login to view URL] gave VLC media player 2.2.6 Umbrella (revision 2.2.6-0-g1aae78981c) [0000000000971608] pulse audio output error: PulseAudio server connection failure: Connection refused [0000000000899118] core libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface. [0000000000971608] alsa audio output error: cannot open ALSA device "default": Device or resource busy [0000000000971608] core audio output error: module not functional [00007fcbdcc02b68] core decoder error: failed to create audio output This behaviour (i.e. sound first working and then not working) is similar to what happened before the installation of pulseaudio on Friday. So the cause of the loss of sound remains a mystery, I'm afraid.