Rescatux y supergrubdisk

Rescatux supergrubdisk.org/rescatux
Rescatux is a GNU/Linux rescue cd (and eventually also Windows) but it is not like other rescue disks. Rescatux comes with Rescapp. Rescapp is a nice wizard that will guide you through your rescue tasks.
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Super Grub Disk www.supergrubdisk.org/
  

Difference between Super GRUB Disk and Super GRUB2 Disk GRUB2 is a complete rewrite of GRUB, and Super GRUB2 Disk is a complete rewrite as well. As Super GRUB2 Disk uses GRUB2, the differences between GRUB Legacy and GRUB2 also apply to the different versions of Super GRUB Disk.

Perhaps the most notable difference between Super GRUB Disk based on grub legacy and Super GRUB2 Disk is that Super GRUB2 Disk does not write to the disk at all, and so cannot rewrite the MBR.

Super GRUB2 Disk can only be used to boot a broken system, it cannot fix it directly. Though once a system is booted, re-installing grub is usually just a matter of running “grub-install /dev/sda”.

While there are some features of Super GRUB Disk based on GRUB legacy that will never be included in Super GRUB2 Disk, the opposite is also true. For instance, Super GRUB2 Disk supports booting OSX, loop booting from iso files, booting an OS from USB without USB support in the BIOS, and other features that are not possible with GRUB legacy.

• More documentation about Super Grub2 Disk
• Discuss on how to use Super Grub2 Disk to solve your problems on the forum
• Download Super Grub2 Disk

Reparando un multiboot con ubuntu 10.04 o 10.10 Fuente

Arranca desde el cd o desde donde tengas el Super Grub Disk y te aparecerá una pantalla como la primera imagen de esta página (arriba)
Selecciona la 1 opción. Si el grub fue destruido al instalar el "maravilloso" windows prueba con la 3 opción. Te mostrará los SO que tienes instalados para que elijas con cual quieres arrancar.

Llegados a este punto ya habrás arrancado Ubuntu, ahora abre un terminal y vamos a recuperar el grub:

sudo grub-install --recheck /dev/sda [/b]

(Cambia sda por tu disco duro, sda es el 1, sdb el 2 y así sucesivamente)

Y por último actualiza las entradas del GRUB:
sudo update-grub

Y ya tendrás el GRUB reparado.