System sounds and notification sounds have stopped working in wind

-- System sounds and notification sounds have stopped working in windows
vista home premium?
they were working just stopped no new installations, they will play via
windows media player and sound works in programs and games and whilst playing
media?

they were working just stopped no new installations, they will play via
windows media player and sound works in programs and games and whilst playing
media, there are no conflicts and all the volume sliders in control are on
none muted, windows will not play the sounds in the windows sound scheme
selector either?
Ant