grub error: you need to load kernel first

From grub-rescue type set then hit the Tab , it will help you to set the first parameters , e,g.:

set prefix=(hd0,gpt2)/boot/grub
set root=(hd0,gpt2)
insmod normal
normal 

you need to load kernel first

To load the kernel forward with the following commands:

insmod linux
linux /vmlinuz root=/dev/sda2
initrd /initrd.img
boot 

Change /dev/sda2 with your root partition , change gpt2 with msdos if you don't have a GUID partition table.

To correctly set your boot parameters, see Ubuntu documentation : search and set

You have to define a kernel file and usually an initrd file and the kernel command line, too, before you can run the boot command (see the Grub documentation).

Normal boot media offer a menu from which you can select and entry. A Grub command line is not for you. Either you are using your Grub wrongly or you should use a different boot medium.