You can get one from Toshiba if you don't have any of the disks that came with the laptop. Or there may be a recovery partition on the hard-drive if the system will see it. Will be an option to get to it at boot time.
Keep in mind doing a system restore like this will wipe out anything on the drive.
The error may also be happening due to a bad disk. You may want to buy a new hard-drive and install Windows on that instead of using the old one.