during moving my root partition, i used the old grub and installed the old grub on harddisk:
grub grub > setup (hd0)
now how could i install GRUB2 on harddisk?
The easiest way is to boot to a Linux installation that has Grub2, and run its
If you're having trouble booting your existing installation, try a rescue/live Linux on CD or USB. Many distributions' install disk are capable of restoring the bootloader. An OS-agnostic rescue disk for Grub2 is SuperGRUB2Disk.