Hi I am a new mac user and have a macbook where I think the harddisk is broken. When I start it up I see a folder with a question mark in it. If I start it up in target disk mode and connect it to another mac I only get the dvd drive mounted (if there is a dvd in the macbook). I have read that I can test if any hardware is failing with the dvd that came with my mac, but I cant find those DVDs. Can I download them or ask for replacements somewhere?