After installing default factory windows xp from VAIO VGN-NR, and hence removing the Ubuntu on its hard drive, the grub does not allow the windows to boot up properly, giving the prompt: "no such partition" and grub rescue appears.
The Windows can not be recovered by rescue mode, since the administrator password of newly installed default windows (from hidden drive on the laptop) is not known to me.
Booting up with live-Ubuntu and trying to erase the MBR did not help a bit.
dd if=/dev/null of=/dev/sdX bs=446 count=1
I can simply install another windows on it, fixmbr and fixboot it and re-install the original factory windows. But I'm not like that. I want to find a way through, not around. Any suggestion?