Missing folders

[Grizzly]

Hi

Having an odd thing happen, I had setup an external USB to run 16.04.5, it runs 

fine on the netbook I set it up from, when I try to boot it on my desktop it 
throws error boot/grub/i386-pc/normal.mod not found & drops to 

Grub Rescue>

ls (hd0,msdos1)/boot/

shows only / 

i.e. no grub folder, but if I run a live session & inspect that same disk 
/boot/grub/i386-pc/normal.mod is there

what I did I miss or do wrong?