Sorry if i expressed wrong, i just wanted to say to Boot-Repair can be a useful software for Debian.
Here is the long description (thanks Thomas for your advice):
Description: Graphical tool to repair boot problems
In some situation, you might loose access to one or several of
your operating systems, because of a buggy update, a bootloader
problem, a broken filesystem, or after installing a new OS (e.g.
installing Windows breaks Linux bootloader).
.
Boot-Repair is a graphical tool that will repair these problems,
generally by reinstalling GRUB, which then restores access to the
operating systems you had installed before the issue.
.
Boot-Repair also has advanced options for reinstalling GRUB, adding
kernel options, restoring a generic MBR, or repair a broken filesystem.
It can also restore the original bootsector if it has been saved
previously by Clean-Ubiquity.
Screenshots:
https://sourceforge.net/p/boot-repair/home/Home/
Regards
Yann