MacBook dosen't start

Ok, so Ive been all over the internet researching for the solution for my problem. When I start up my MacBook it does everything great, it chimes it gives me the dim blue screen with the Apple on it and the little circle going round and round. After five minutes or more of that same screen with the circle going round and round, my computer just turns off and nothing else. I found on the internet to press "Command" and "S" then I type "fsck -fy" i have also tried "/sbin/fsck -fy". When i do either it gives me a error message. I also tries using the DVD while i start up my mac. I do the verify permition/disk and another error comes up. Any ideas?
if u need anything ask and ill try to clarify for you
Thanks

Your hard drive may have gone south. Try re-setting the PRAM and NVRAM first and see if that helps.

Resetting your Mac's PRAM and NVRAM

If no joy, the hard drive may be bad.

Regards.

ok I tried that. Nothing happened. So I guess it's a problem with my hard drive. What can I do to fix it? And one other thing. If I installed the OS again could that help? And if I do will it erase everything on the computer? Btw I don't live in the states so I can't go to an apple store. Should have bought a vaio...