Formatting the hard drive with the Vista installation would wipe out the drive and render it useless as a boot device. So, the machine no longer has Vista installed and will not boot up due to the drive being formatted. A Vista installation DVD would be needed to reload a new installation of the OS onto the hard drive. The drive could be installed on another system to check if all the data has been lost before formatting and reinstalling Vista with a Vista installation DVD. Check with the manufacturer for any system DVD that may be available for purchase.