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I have Jolicloud OS and Windows 7 dual boot and I deleted the Jolicloud partition. Next time I turned the computer on it said:

error unknown filesystem grub rescue

So I reinstalled Jolicloud and turned it off and on, but it still comes up with the same error.

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You deleted the Jolicloud partition, so you were trying to get rid of it? In that case, you'll need a windows 7 disc to replace grub with the windows 7 MBR. I've never had to do this with win7, but it's easy in XP. – Rob Sep 21 '11 at 15:25

Sounds like you deleted your grub config.

you need to install grub again. Depending on which grub you have installed,

get yourself an ubuntu or similar boot disk and then

use the following command to identify your disk descriptor

sudo fdisk -l


sudo apt-get install grub
grub-install /dev/<disk name>


user@ubuntu:~$ sudo fdisk -l
    Disk /dev/sda: 300.1 GB, 300069052416 bytes
255 heads, 63 sectors/track, 36481 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x045a0459

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1       31871   256003776    7  HPFS/NTFS
/dev/sda2           31872       36480    37021730+   5  Extended
/dev/sda5           36290       36480     1534176   82  Linux swap / Solaris
/dev/sda6           31872       36289    35487522   83  Linux

Partition table entries are not in disk order
user@ubuntu:~$ sudo grub-install /dev/sda
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