If you are stuck at the grub rescue> prompt, follow these steps to troubleshoot:
At the grub rescue> prompt, run:
ls
You will see a list like:
(hd0) (hd0,gpt1) (hd1,gpt2) (hd2,gpt1) ...
Check each partition individually:
ls (hdX,gptY)/
Replace X and Y with the appropriate numbers.
You are looking for a partition that does not return an unknown filesystem error and ideally shows folders like:
./ ../ lost+found/ boot/ ...
If you see a /boot/ directory, that's a good sign.
Once you find the correct partition:
set root=(hdX,gptY)
If you found a /boot/grub folder inside it, set the GRUB prefix and try to load the normal mode:
set prefix=(hdX,gptY)/boot/grub
insmod normal
normal
If successful, you should get the normal GRUB boot menu.
Provide the following details for further help: