It may happen that your OS will not boot, the boot loader might be corrupted. What to do in this case? Fortunately, there are several specialized utilities that will help you to load the operating system and then fully restore the boot loader.
Earlier I already wrote about restoring GRUB boot loader. You can find similar articles at this link. So What can do Rescatux?
How to put Rescatux into a CDROM or a USB or see here
~ 672 MB Size
On the first screen that you will see, you will be able to choose the upload option: is a Rescatux 32-bit, Rescatux 64 bit, or Rescatux autodetect. There is also the opportunity to load only the Super Grub2 Disk, which was mentioned above. Leave the first paragraph - Rescatux autodetect. Detect any OS Selecting this option SG2D (Super GRUB2 Disk) will scan all partitions on all disks with the aim to detect operating system and then create a menu where you can select any of the OS found for subsequent launch. If You want to view commands or to edit a menu item, you can press "e" and then "ctrl+x" to launch on performance. Supports the following OS: - GNU/Linux (although at the time of writing this manual support for separate /boot partition is not implemented); - FreeBSD; - Mac OSX/Darwin; - MicrosoftWindows - all versions; What can do Super Grub2 Disk?
Boots into many systems and GRUB2 ones!
Helps you to fix your GRUB or GRUB2
Loads Grub legacy confs (menu.lst)
Optional LVM / RAID support
How to put Super Grub2 Disk into a CDROM or a USB or see here