Dead Sound Card

I have a client whose sound has suddenly died, after running well since the system was installed. (Six months?? A bit more?) The obvious explanations are user error (clicked something without realising) or dead hardware. She is running Debian Wheezy with TDE 3.5.13.2 on an oldish Dell laptop. Since I haven't got the laptop here, I haven't got its specs. I cannot have the laptop to work on for the moment, since she is using it a lot for now. All suggestions or explanations welcomed, Lisi