Grub Error, no such Partition found- fixing in ubuntu

Firstly, insert your current linux os bootable using either cd or usb. Now, enter into the terminal by selecting the trying option. After, taking the terminal type

sudo fdisk -l


which prints the every the partition. Select your linux partition. Mount the linux partition using mount command, ie. suppose consider /dev/sda6 is your linux partition, mount it by the following command. Before that create a directory for mounting the drive, ie,

sudo mkdir  /media/sda6

now after creating, mount the drive in the created 'sda6' directory

sudo mount   /dev/sda6  /media/sda6

after mounting, type the below command for installing grub from cd or usb

sudo grub-install --root-directory=/media/sda6 /dev/sda

thus u have installed the grub