Macbook 13'' 2007 not turning on, help!!

I have a 2007 white 13'' macbook which wont start, ive tried all of the resets and it wont start. the charging light on the cable lights up and the light on the front lights up but the screen stays black and doesnt play the startup chime. i've kept the ram at the same 4gb since i bought it, nothing has changed, but it wont turn on.