Posted 21 July 2012 - 05:19 PM
I'll offer another way in that I've used many times when installs went wrong ...
Find a live cd that boots with grub legacy; older Mepis, Suse, Ubuntu, others. Boot from that cd, and when the first screen comes up hit Escape, then C. This will get you into grub command mode, loaded from the cd. Then at the prompt, enter ...
grub> kernel (hd0,7)/boot/vm ..... and hit tab, which will offer to complete that line, resulting in ...
grub> kernel (hd0,7)/boot/vmlinuz ... then add
grub> kernel (hd0,7)/boot/vmlinuz root=/dev/sda8 ro .... and then finally
grub> initrd (hd0,7)/boot/in ... hit Tab to get
grub >initrd (hd0,7)/boot/initrd.img .... and finally,
and that will cause it to boot the system that is on /dev/sda8. Change that to pick the partition you want to boot. Not all distros use an initrd, but many do, will do no harm to ask grub about it.
And then, once booted, you are in the real OS with all its environment, etc.
If you know where the original used-to-work menu.lst is located, then you can just say
grub> configfile (hd0,7)/boot/grub/menu.lst
which will bring up the menu.lst you are accustomed to seeing; select as usual.
Note -- re hd0 vs hd1 ... grub takes it's clue from the bios boot order. If you don't see what you expect, try using (hd1,7) where I used hd0 above.