sound mysteriously stopped working in Debian
 

We have a computer running Debian Squeeze.Until about 3 weeks back,sound was working fine for all the users.Then suddenly one day,sound stopped working for one of the users,it works only intermittently for another one(it works some of the time,it even stops suddenly in the middle of playing a song),for the third user sound is still working fine.

could someone please tell me what is the problem ?

That is Debian testing not stable.

Is ALSA installed?
Try reconfiguring it.

or is it phonon?

First upgrade your system

su
apt-get update && apt-get upgrade

yes..it worked after upgrading :)

thank you!