OK, don't hate me for this, but I tried out Ubuntu and while it's pretty solid, it can't playback videos (specifically .mkv's) as well as Windows with all the necessary codecs installed. Which, aside from gaming, is what I mainly use my PC for. So I want to uninstall Ubuntu, which I put on a separate hard drive. I tried doing it once before, but it fucked my computer because GRUB (I think) kept looking for Ubuntu or something, and when it couldn't find Ubuntu, it flipped out and wouldn't let me start my computer. Can someone give me step-by-step instructions on how to remove Ubuntu from my computer and free up that hard drive so I can use it with Windows again?