grub install

[spiff_s50]

my brother is having problems with his dual boot system,
i tried to use knoppix to reinstall grub to the MBR
knoppix wouldn't let me because i wasn't root (don't know root password).
i was using knoppix 3.9
what is it's root password? can someone explain how to reinstall grub (with pre existing files)

i am not a noob...
but i still suck at this...
i think i know how to install grub...
but i'm not sure...

[OErjan]

as to the password. here is a link with LOTS of info.
http://www.knoppix.net/forum/viewtopic.php?t=11500
as to how to resurect grub. hmm, links and some text folows.
http://www.knoppix.net/wiki/Rescue_FAQ
the answer is here. a combination of the first and second questions. and the adition on reinstalling grub
chroot to the r/w mounted / of the old system (let us call it /mnt/hdaX)

sudo chroot /mnt/hdaX
now do

mount -a

now reinstall grub (no expert on that, here you have some links).
http://portal.suse.com/sdb/en/2002/09/fhassel_grub_overview.html
here is a qoute from the link.

Hint: Since the install command is already included in the file /etc/grub.conf, the easiest procedure consists of starting GRUB in "batch" mode in a Linux shell and having the file /etc/grub.conf read out:

grub --batch --device-map=/boot/grub/device.map </etc/grub.conf

and here is a link to the grub- Linux man page
http://www.die.net/doc/linux/man/man8/grub.8.html