Why won't my MacBook boot up.

I have a 15 inch non unibody MacBook pro that won’t turn on. It originally turned on when I got it last year no problem. Then it started to take longer and before harder to turn it on. I recently took it out of storage to turn it on and can’t get anything out of it. Last time i had to do something with the ram when it was plugged in to turn it in. Is it the pram battery?