OK, I think we really have to stop the thread now before we get into trouble as it's not really Park related and there's a limit one can do with minimal information.
(I notice you haven't answered most of my questions so I can't really help any more without having the laptop here

- they were all asked for good reasons, honest).
There are problems with this make of laptop and sounds (Google the words I gave before - lots of suggestions there).
The solution depends on a number of factors including upgrading from XP to Vista, whether the problem has suddenly started or whether it's from after an upgrade or since you bought it.
As a final suggestion, open the sounds and audio devices in control panel and look at EACH tab and see if anything is obvious - check EVERYTHING. (Make sure the mute tab isn't checked!!!) - I have known sound being allocated to some strange things! - like a USB turntable (oops, it did that to me when I installed the drivers and I lost all my sounds).
Go to the "sounds" tab and check that your laptop plays the Windows sounds.
If it does, it isn't the machine, it's the player.
If it doesn't, it's either a loose wire inside the laptop (more or less as SirLamer indicated) or your settings are wrong. You'll need to think back what you installed or did since the last time it worked.
If you have upgraded to Vista, update all your sound drivers to the latest versions and check also that sound it enabled in the BIOS.
If all that leaves you scratching your head, take it to a PC repair shop :

Good luck