Help me restore grub for arch installation

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http://unix.stackexchange.com – After I've installed windows xp for dual booting, I need to restore grub of my archlinux installation. I did it a lot of times with windows 7, but this time heavens decided to torture me. I have opensuse liveKDE usb drive inserted into my laptop. My currect drive is /dev/sda with /dev/sda1 -> archlinux /; /dev/sda2 -> /home; /dev/sda3 -> windows xp. In liveKDE konsole I mount my /dev/sda1 to /mnt/arch, chroot /mnt/arch /bin/bash and run grub. Trying root (hdX,Y) I get "selected disk does not exist". So I try grub-install /dev/sda, which gives me "Not found or not a block device". I have tried (HowTos)