Attention Nerds

I don't think this is a avery difficult problem but I recently had to wipe my hard rive clean and start anew on my laptop. Since then I have lost the ability to play DVDs on this friggin' thing. Anybody know what software I need to download? I have done some preliminary searches and downloaded a few programs that did not work. Please help. I am too busy/lazy to spend a lot of time on this.