Here are the step-by-step instructions on how to use Diskpart:
- Insert your Windows CD into the optical drive and boot into a command prompt.
- Type diskpart to load the utility.
- Type list disk. Diskpart will list all the hard drive(s) on your computer.
- Type select disk x (where x=the number of the disk you want to zero out). Diskpart will return "Disk x is now the selected disk."
- Type clean all and Diskpart will completely zero out the entire disk.