Remove the battery and plug the AC plug in. Power it on...
[If this works, I'd imagine your battery is the issue]
If that doesn't do anything, remove the AC plug, take the hard drive out, plug the AC back in, Power it on...
[If this works, suspect your HDD]
If you still don't have anything (blank screen), then I'd suggest trying an external monitor (you should have a VGA socket somewhere on your laptop)...
[If this works, your laptop screen probably has a power supply issue - Loose wire maybe?]
If you can't get any image on either screen, I would suspect the motherboard is at fault...
[Probably best to buy a new laptop or taking it to a PC repair shop. Replacing a laptop motherboard isn't something you want to do personally]
Hope this helps.