Rescatux was the standard for grub repair in MBR and EFI systems. It has a ton of tools. Recent updates arent compatible with new machines and the system wont load anymore. If you have a GPU+CPU machine (like a AMD A6 R4) forget to use rescatux.
However if your machine is compatible, use rescatux as it's probably the best tool for repairing boot problems, disk management and thousand of thing more.
Rufus - Rufus is a piece of software that allows you to transform a portable drive, like a flash drive or other USB drives, into a bootable drive that can be used for a variety of purposes. Read more about Rufus.
Hirens BootCD - Hirens BootCD is a powerful, all-in-one boot disk utility that will help you resolve and make reformatting your computer easily.
Balena Etcher - Flash OS images to SD cards & USB drives, safely and easily.
Ultimate Boot CD - The last Boot CD you'll ever need. You need the Ultimate Boot CD if you want to:
UNetbootin - UNetbootin is a utility for creating live bootable USB drives. The name of the software is short for Universal Netboot Installer, and its most prevalent use has been to create bootable versions of Linux distributions on a USB drive.
Finnix - Finnix is a small, self-contained, bootable Linux CD distribution for system administrators, based...