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.
Charity Engine - Charity Engine takes enormous, expensive computing jobs and chops them into 1000s of small pieces...
Hirens BootCD - Hirens BootCD is a powerful, all-in-one boot disk utility that will help you resolve and make reformatting your computer easily.
BOINC - BOINC is an open-source software platform for computing using volunteered resources
Finnix - Finnix is a small, self-contained, bootable Linux CD distribution for system administrators, based...
Apache Mesos - Apache Mesos abstracts resources away from machines, enabling fault-tolerant and elastic distributed systems to easily be built and run effectively.
Ultimate Boot CD - The last Boot CD you'll ever need. You need the Ultimate Boot CD if you want to: