Critical Failure, need to reinstall

I unfortunately in my naivety, destroyed my Ubuntu 18.04 LTS installation on my HP pavilion laptop in one line involving the "rm" command.

I can only access the GRUB command line by pressing F10 at start up, I have altered the BIOS settings to take precedence with booting from a USB, and saw this command while trying today:

sudo dd if="ubuntu-18.04-desktop-amd64.iso" of=/dev/sdX bs=8M

So my question is, will the GRUB command line terminal recognize this, and how can I first determine the location of the USB that I have put in with the .iso file?

I can't describe how grateful I would be here I have tried quite a lot of things, but I never imagined I could damage my OS so badly like this