Grub problem - Command prompt

Question

Update: Thanks to all who helped. I gave up and am going to re-install. Not the end of the world, no files will be lost :-) This time will be backing up grub haha. Thanks again, I really appreciate the community's help on this.

I was going along fine when the new pae kernel came down, and it had some bug where the sound was all messed up.

So I used startup manager to choose the older pae kernel and rebooted. But startupmanager must have fuXXored my grub.

When I re-booted, I get thrown directly into memtest and thats it.

I tried to re-install grub using the live disc method that I found in many places. That changed something so I get a prompt and the message: "GNU grub version 1.99 ubuntu. Minimal BASH-like editing is supported. Type help for complete list."

But then I tried the live CD fix again and now am back at the memtest...

What can I do to get my system running again?

UPDATE: Just to be clear,when I start up I get a blinking cursor in the top left, and the word 'ON' in the middle of the screen. Then, after a good minute or two, the memtest starts.

Answer 1

insmod gzio
insmod part_msdos
insmod ext2
search --no-floppy --file --set=root /boot/grub/grub.cfg
linux   /boot/vmlinuz-3.0.0-16-generic
initrd  /boot/initrd.img-3.0.0-16-generic`

You'll have to know your kernel version though

Answer 2

I'll just make a different answer for this one. It's the same principle as the live-cd, but probably a little different than you did.

Enter the LiveCD, mount your drive, note its mountpoint. Then, open a terminal:

sudo mount --bind /dev /[mountpoint]/dev
sudo chroot [mountpoint]
mount -t sysfs none /sys
mount -t proc none /proc
mount -t devpts none /dev/pts
update-grub
umount /sys
umount /proc
umount /dev/pts
exit
umount /[mountpoint]/dev
reboot

if update-grub doesn't work (which it should) then grub-install /dev/sdaX surely will. I'm assuming you also know the partition it's installed on? If not you can check the Gparted on the LiveCD to be sure.

Answer 3

It sounds like you tried something like this already, but I don't know exactly what you tried, so I'll post it anyway. Pay attention to the X and Y and make sure you get them right. I have used this method many times and it has always worked, but please forgive me if this is what you already tried.

This is a quick and simple method of restoring a broken system's GRUB 2 files. The terminal is used for entering commands and you must know the device name/partition of the installed system (sda1, sdb5, etc). The problem partition is located and mounted from the LiveCD. The files are then copied from the LiveCD libraries to the proper locations and MBR. If, for example Windows is on sda1 and Ubuntu is on sda5, and Windows has overwritten the MBR, then the target for grub installation will be /dev/sda5, and the MBR in the boot sector of sda will be re-written for grub.

This operation will write to the MBR and restore the modules and core.img to /boot/grub. It will not replace or restore grub.cfg or fix corrupted files.

Boot the LiveCD Desktop.

Open a terminal window.

Determine the partition with the Ubuntu installation. The fdisk option "-l" is a lowercase "L".

sudo fdisk -l

If you're not sure of the partition, look for one of the appropriate size or formatting.

Running sudo blkid may provide more information to help locate the proper partition, especially if the partitions are labeled. The device/drive is designated by sdX, with X being the device designation. sda is the first device, sdb is the second, etc. For most users the MBR will be installed to sda, the first drive on their system. The partition is designated by the Y. The first partition is 1, the second is 2. Note the devices and partitions are counted differently. Mount the partition containing the Ubuntu installation.

sudo mount /dev/sdXY /mnt

Example:

sudo mount /dev/sda1 /mnt

Note: If the user has a separate /boot partition, this must be mounted to /mnt/boot Note: If the user has a separate /home partition, this must be mounted to /mnt/home. Encrypted home partitions should work.

Run the grub-install command as described below. This will reinstall the GRUB 2 files on the mounted partition to the proper location and to the MBR of the designated device.

sudo grub-install --boot-directory=/mnt/boot /dev/sdX

Example:

sudo grub-install --boot-directory=/mnt/boot/ /dev/sda

Reboot

Refresh the GRUB 2 menu with

sudo update-grub