Stuck at Grub prompt

[bricabrack]

Hello all, I recently attempted to upgrade from Natty to Oneric but with disasterous results.
I am now stuck at the Grub rescue prompt and can`t boot into Ubuntu or Vista (my other op sys) nothing seems to work. It won`t boot from the CD either. Help required urgently by a silver surfer. Thanks in anticipation.

[oldfred]

You should be able to boot from CD and may need that to repair system. Sometimes a total power shut down (cold boot) helps reset things. You have to make sure BIOS is set to boot CD first or if your system has a one time boot key (f12 on my system) use that to choose to boot CD. You do need a liveCD of the current version to make repairs.

You may be able to boot with these instructions if install is ok.
Grub Rescue Prompt Megathread - drs305
http://ubuntuforums.org/showthread.php?t=1594052
HOWTO: Boot & Install Ubuntu from the Grub Rescue Prompt
http://ubuntuforums.org/showthread.php?t=1599293

Otherwise you need liveCD to chroot into your system and update/repair.
Reinstall grub2 - Short version & full chroot version
https://help.ubuntu.com/community/Grub2#Reinstalling%20GRUB2
Grub2 info & full chroot version - also see METHOD 3 - CHROOT:
https://wiki.ubuntu.com/Grub2#Recover%20Grub%202%20via%20LiveCD
How to restore the Ubuntu/XP/Vista/7 bootloader (Updated for Ubuntu 9.10 and later with grub2) by talsemgeest
http://ubuntuforums.org/showthread.php?t=1014708
chroot with screen shots
http://opensource-sidh.blogspot.com/2011/06/recover-grub-live-ubuntu-cd.html

[bricabrack]

Hello all, Firstly many thanks to oldfred for the reply to my query. Unfortunately after trying the links supplied I am still experiencing problems with booting into Ubuntu. I can`t progress beyond boot prompt! Anybody got any ideas because my hair is rapidly turning white.

[oldfred]

When you say boot prompt. Is that grub rescue or grub> ?

If system is otherwise bootable sometimes Supergrub helps. But you may have video issues, or other system issues. Can you boot LiveCD?

http://www.supergrubdisk.org/
http://www.supergrubdisk.org/wiki/Main_Page

If only minor repairs are required, this may help & from it you can run the boot_info_script that documents your system so we may be able to see exactly what is wrong.

Boot Repair:
https://help.ubuntu.com/community/Boot-Repair