If it is indeed the hard drive, you will need to buy a new hard drive. Probably get one for under $50. (Very easy to put in) Then you will have to install Windows. For that you will need the disk. You may be able to get them from the manufacturer like ss202sl said. Or any version of Windows 7 will work if you have one (as long as it is the same version: home or ultimate etc, as the COA on your laptop)