First of all, check this is you have a macbook pro.
Also, what model laptop is this? How old is it? We'll need to know this to solve your problem.
If you have a Powerbook G4:
http://docs.info.apple.com/article.html?artnum=88077
What happens if you press the button on the battery?
If you have an iBook, see this:
http://docs.info.apple.com/article.html?artnum=58450