First, please read the LQ rules
, especially the part about use of offensive language. The forum has members of all ages and backgrounds.
Next, I am not a user of M$ software so my answer is not definitive, but as restrictive as they are about people actually using their stuff, I doubt that you can just boot it off a USB drive. Grub should really have nothing to do with that. And if your friend reformatted the drive then grub is gone anyway.
You must set the computer's BIOS to recognize the USB device as bootable, then visit an M$ forum or website to find out what their requirements are for running from that device. GNU/Linux is no longer in that picture.