I have a multiboot system set up. The system has three drives. Multiboot is configured with Windows XP, Windows 7, and Ubuntu - all on the first drive. I had a lot of unpartitioned space left on the drive and was reserving it for adding other OSes and for storing files there in the future. One day I went ahead and downloaded Partition Wizard and created a logical NTFS partition from within Windows 7, still some unpartitioned space left over. Everything worked fine, until I rebooted the computer a few days later. Now I'm getting: error: unknown filesystem. grub rescue First of all I was surprised not to find any kind of help command, by trying: help, ?, man, --help, -h, bash, cmd, etc. Now I'm stuck with non-bootable system. I have started researching the issue and finding that people usually recommend to boot to a Live CD and fix the issue from there. Is there a way to fix this issue from within grub rescue without the need for Live CD? UPDATE By following the steps from persist commands typed to grub rescue, I was able to boot to initramfs prompt. But not anywhere further than that. So far from reading the manual on grub rescue, I was able to see my drives and partitions using ls command. For the first hard drive I see the following: (hd0) (hd0,msdos6) (hd0,msdos5) (hd0,msdos2) (hd0,msdos1) I now know that (hd0,msdos6) contains Linux on it, since ls (hd0,msdos6)/ lists directories. Others will give "error: unknown filesystem." UPDATE 2 After the following commands I am now getting to the boot menu and can boot into Windows 7 and Ubuntu, but upon reboot I have to repeat these steps. ls ls (hd0,msdos6)/ set root=(hd0,msdos6) ls / set prefix=(hd0,msdos6)/boot/grub insmod /boot/grub/linux.mod normal UPDATE 3 Thanks Shashank Singh, with your instructions I have simplified my steps to the following. I have learned from you that I can replace msdos6 with just a 6 and that I can just do insmod normal instead of insmod /boot/grub/linux.mod. Now I just need to figure out how to save this settings from within grub itself, without booting into any OS. set root=(hd0,6) set prefix=(hd0,6)/boot/grub insmod normal normal UPDATE 4 Well, it seems like it is a requirement to boot into Linux. After booting into Ubuntu I have performed the following steps described in the manual: sudo update-grub udo grub-install /dev/sda This did not resolve the issue. I still get the grub rescue prompt. What do I need to do to permanently fix it? I have also learned that drive numbers as in hd0 need to be translated to drive letters as in /dev/sda for some commands. hd1 would be sdb, hd2 would be sdc, and so on. Partitions listed in grub as (hd0,msdos6) would be translated to /dev/sda6.