I have a laptop thinkpad that I believe I need to reinstall an operating system. I can get to the BIOS. I have a disk from old cell computer that says operating system back up? Or will I need to buy the program. I'm a novice at "fixing" computers for my family so this is a bit above me for having to work in the BIOS menus. When I put the disk in it looks like it might run the disk but in the end gives me error can not find... Any help would be nice