MajorGeeeks published an overview of five bootable ISO images to boot and repair your computer.
5 Bootable ISO's to Boot and Repair Your Computer for Free
If your computer won't boot, not all is lost. There are five free apps that you can use to boot from CD, DVD, or a thumb drive to run diagnostics, make repairs, back up files, and more.
5 Bootable ISO's to Boot and Repair Your Computer for Free - MajorGeeks