GRUB Rescue - setting boot and prefix again and again
I got a solution for this type of problem if grub rescue> prompt occurs in booting time and you have to write a code like:
grub rescue> ls
grub rescue> set boot=(hd0,msdos*)
grub rescue> set prefix=(hd0,msdos*)/boot/grub
grub rescue> insmod normal
grub rescue> normal
After boot Linux/Ubuntu based OS will load then open a terminal and write the command:
useranf@ ~ $ sudo update-grub
then type this command:
useranf@ ~ $ sudo grub-install /dev/sda
after these operation now finally reboot your system.