A free bootable CD that contains a multitude of tools for analyzing, recovering, and fixing your computer even if its operating system does not start
Hiren’s BootCD PE (Preinstallation Environment) is a restored edition of Hiren’s BootCD based on Windows 10 PE x64. PE version is being developed by Hiren’s BootCD fans. it supports UEFI booting and requires minimum 2 GB RAM.
SystemRescue is a Linux system rescue toolkit available as a bootable medium for administrating or repairing your system and data after a crash. It aims to provide an easy way to carry out admin tasks on your computer, such as creating and editing the hard disk partitions.
The Parted Magic OS employs core programs of GParted and Parted to handle partitioning tasks with ease, while featuring other useful programs (e.g. Partition Image, TestDisk, fdisk, sfdisk, dd, and ddrescue) and an excellent set of documentation to benefit the user.
Trinity Rescue Kit or TRK is a free live Linux distribution that aims specifically at recovery and repair operations on Windows machines, but is equally usable for Linux recovery issues. Since version 3.
ALT Linux is a set of RPM-based, APT-managed operating systems built on top of the Linux kernel and Sisyphus package repository branches. ALT Linux Rescue is, well, the disaster recovery tool.
Grml provides an excellent selection of software packages for installation, deployment and system rescue. You'll get sysadmin's favourite tools. Choose between a x86 and an amd64 version depending on your needs or just grab the multiboot ISO grml96, providing 64bit and...
Hoek’s Tools is a vast collection of portable utilities for the management, diagnosis and repairing of computer problems, recover lost or deleted files or cracking passwords. There are literally hundreds of utilities.Discontinued
The project is no longer updated and a download is no longer provided on the official website, but you can still download last version, 0.1.001, released on April 20, 2013. See the link to the setup file in the comments.