Serious GRUB booting problem after install Ubuntu 9.10beta for testing it.

[Rashkae]

Joseph Cooper wrote:
> Hi, panicked list newbie here! So please excuse me if I'm not conforming to
> the posting etiquette here, but this was the only site I could find where
> someone seems to have a similar problem to me, and it is very urgent so I
> decided to jump in!
> 
> I seem to have done something similar to the OP, I have Linux Mint 7 (i.e.
> Ubuntu 9.04) installed on my laptop (a hard drive, not SSD, though I doubt
> that makes any difference) and tried to install the Karmic beta on my
> external USB HDD. Unlike the OP I had no other OSs on there, though the
> FAT32 disk did have some data on it so I went for guided resizing. I'm
> unfamiliar with the new Ubiquity and so had to skip back a stage in the
> partitioner after a 2.5gb partition had already been made without me
> realising, since that wasn't big enough; I then cereated another larger
> partition, and it listed the 2.5gb as "free space". Not sure if that space
> is still free or if this was the cause of my problem.
> 
> Anyway, like the OP, I get Error 17 when I boot with the external turned on,
> though I do not get an option to continue, I have no options and must
> hard-reboot. Again I get "no such disk" when booting with the external off,
> and am given a grub rescue> prompt. I tried the grub rescue commands
> mentioned but only the first one, ls, worked; I am told that "root is not a
> valid command" or similar, no matter what I put in the (hd0,X). Trying any
> of the other commands just returns another "no such disk". All my files are
> still there on my hard drive, though I would very much like to resolve this
> without having to reinstall.
> 
> Any idea why the root command isn't working for me, and what I can do to
> boot back into Mint 7? At this point I don't care what happens to the
> external and just want to be back where I was when I started! I had thought
> I did the whole thing without touching my internal drive, but obviously
> not...
> 

You overwrote the mbr of your system with Grub 2 (the shiny new Grub) No
need to panic though.

You will need to boot from a Live CD (the Ubuntu installation CD for
9.04 or Mint will do nicely, but almost any other boot cd will also work
so long as it includes grub) and run grub-install /dev/sda from a
command shell. (assuming that your hard drive is found as sda)