I know this sounds stupid, but are the speakers plugged into the correct hole on the soundcard?  I only ask, because my mate had exactly the same problem the other week, and he'd plugged the speakers in the wrong hole!

If not that, are there no sounds at all, or is it just when trying to play CDs?  I was wondering if Sound Properties (where all the slider volume controls are) might be where to find the problem?

Is the media player of your choice associated with the CD files, and is it starting properly?

Sounds like ( no pun intended  ) Adept will be on the rght track Clive ,make sure the wires are connected from the cd rom to the soundcard (or motherboard if its on board sound) and that youre playing the cd from the cd rom drive and not the writer

It's not the machine that Adept built, but an older 600MHz Win 98 computer which I donated to someone.  At the time, I forgot to give her the speakers but Mrs Clive took them to her today and failed to get them to work.  It only has a CD (no CDRw).  They are definitely plugged into the correct hole (it's colour coded)and the sliders are up to full volume.  Wav files don't work either.

Daft question I know, but have you checked that the speakers actually do work?  

The speakers certainly used to work when I last used that computer so I would be surprised if the sound card is faulty.  Mrs Clive checked that the system wasn't muted too.  One thing I've just thought of is that the speakers could be from an earlier computer and that the colour codes are not the same.  I don't know if there is a colour standard for computer peripherals.  The computer is now the prize posession of a group of nuns and it's a bit difficult for me to gain access to it.    I'm not quite sure what you call a group of nuns.      

I'm not quite sure what you call a group of nuns.      

I think it's a gaggle, or am I confusing them with penguins