Macbook randomly shuts off

Hello everyone, I have a macbook pro that shuts off randomly. Sometimes it turns on and runs fine but then will suddenly power off. I do not have applecare so I would like to get some opinions on what could be causing this. I have misplaced the OSx install discs for the macbook so I am without those. However, I have a macbook pro as well and I received installation discs with that for a repair that was done on it, if I use those OS X install discs on the macbook would that work reinstalling the OS? Any input would be much appreciated.
Sincerely,
Rylenol

You could buy the recovery cds from eBay for a few bucks, otherwise try seeking help from a genius.