Macbook Pro won't start up

My 2008 15 inch 2.6Ghz MBP went to sleep and when I came back it wouldn't wake. When I pressed a key the optical drive made a noise and the fans came on but nothing else,m the screen remains black. I shut it down, by holding the power button down, and tried to start it up, again the optical drive made a nosie and the fans come in but no chime. The key board isn't illuminated and the cap lock light isn't lit. I've tried restting the SMC and reseating the ram, I can't reset the PRAM as the start up sequence doesn't seem to begin? Any ideas…?