GRUB error: unknown filesystem

Insert live cd linux, then boot with live cd. But need to be a note that this can be done with live cd linux and can not use live usb linux. Open your terminal then typing the command:

aan@ans:~$ sudo fdisk -l

and you see

Disk /dev/sda: 250.1 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 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: 0x5ae75c57

Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1       14852   119298658+   7  HPFS/NTFS
/dev/sda2           14853       30401   124897312    f  W95 Ext'd (LBA)
/dev/sda5           14853       15362     4096543+  82  Linux swap / Solaris
/dev/sda6           15363       30401   120800736   83  Linux

linux partition is /dev/sda6, follow the command below and don't forget your choose /dev/sda6

aan@ans:~$ sudo mount /dev/sda6 /mnt
aan@ans:~$ sudo mount --bind /dev/ /mnt/dev/
aan@ans:~$ sudo mount --bind /proc/ /mnt/proc/
aan@ans:~$ sudo chroot /mnt/
root@ans:/# grub-install /dev/sda

Please restart your computer and exit live cd linux.