Question: what are the grub rescue commands?
Answer: List the partition you have on the disk. grub-rescue> ls.
The above command display some partition and from these partition find out which has /boot/grub,Which contains several . ... 
set this partition. ... 
Now insert module on kernel using insmod (install loadable kernel module) command. ... 
Restart the machine. ... 
$ sudo update-grub.