Sinon pour le terminal : elementary@elementary:/$ sudo mount /dev/sda1 /mnt
elementary@elementary:/$ chroot /mnt
chroot: cannot change root directory to /mnt: Operation not permitted
elementary@elementary:/$ sudo chroot /mnt
root@elementary:/# sudo grub-install /dev/sda
sudo: unable to resolve host elementary
/usr/sbin/grub-probe: error: cannot find a device for /boot/grub (is /dev mounted?).

A la fin il y a un message d'erreur

J'ai eu un truc assez bizarre :

elementary@elementary:/$ chroot /mnt
chroot: cannot change root directory to /mnt: Operation not permitted
elementary@elementary:/$ grub install /dev/sda
The program 'grub' is currently not installed. You can install it by typing:
sudo apt-get install grub
elementary@elementary:/$ sudo apt-get install grub
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package grub is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
grub2-common grub-pc

E: Package 'grub' has no installation candidate
elementary@elementary:/$

Je savais que tu allais venir chez nous (Ton topic du- 15)

The program 'grub' is currently not installed. You can install it by typing:
apt-get install grub

Sur le chroot ?

Je fais un apt-get install grub normal ?

[HS]Et sinon J'AI TROUVÉE un moyen d'installer aptitude sur ubuntu: Sudo apt-get install aptitude [HS]

root@elementary:/# apt-get install grub
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package grub is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
grub2-common grub-pc grub-efi-ia32 grub-efi-amd64

E: Package 'grub' has no installation candidate

root@elementary:/# apt-get install grub-pc
Reading package lists... Done
Building dependency tree
Reading state information... Done
grub-pc is already the newest version.
grub-pc set to manually installed.
0 upgraded, 0 newly installed, 0 to remove and 75 not upgraded.

install-grub /dev/sda

ou grub-install /dev/sda

root@elementary:/# install-grub /dev/sda
install-grub: command not found
root@elementary:/# grub-install /dev/sda
/usr/sbin/grub-probe: error: cannot find a device for /boot/grub (is /dev mounted?).
root@elementary:/# apt-get install grub2-common
Reading package lists... Done
Building dependency tree
Reading state information... Done
grub2-common is already the newest version.
grub2-common set to manually installed.
0 upgraded, 0 newly installed, 0 to remove and 75 not upgraded.

T'as monté /dev/sda ?

Oui.

Je dois faire quoi ?

rm: cannot remove `/boot/grub/915resolution.mod': Permission denied

/usr/sbin/grub-probe: error: cannot find a device for /boot/grub (is /dev mounted?).

Qu'il installe lilo ou syslinux pour voir si sa change?

Grub repair n'existe pas.

sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update; sudo apt-get install -y boot-repair && boot-repair