GRUB.

Resore GRUB 2.

If you boot to same bit-width kernel (32/64) that have installed you can chroot to main system and recover by your Linux discto commans:

mount /dev/sdX /mnt
sudo mount --bind /dev /mnt/dev &&
sudo mount --bind /dev/pts /mnt/dev/pts &&
sudo mount --bind /proc /mnt/proc &&
sudo mount --bind /sys /mnt/sys
sudo chroot /mnt
grub-install /dev/sdX
update-grub

Check that partition with /boot directory:

$ mount /dev/sdX /mnt
$ ls -l /mnt/boot/grub

Setting text mode resolution on boot.

vga=mode

Specifies the VGA text mode that should be selected when booting. mode defaults to the VGA mode setting in the kernel image. The values are not case-sensitive. They are:

ask

Prompts the user for the text mode. Pressing Enter in response to the prompt displays a list of the available modes. extended (or ext) Selects 80x50 text mode.

normal

Selects normal 80x25 text mode.

number

Uses the text mode that corresponds to number. A list of available modes for your video card can be obtained by booting with vga=ask and pressing Enter.

F00 80x25
F01 80x50
F02 80x43
F03 80x28
F05 80x30
F06 80x34
F07 80x60
F09 132x25
F0A 132x43
F0B 132x50
F0C 132x60
100 40x25
154 132x43
155 132x25
164 132x60
165 132x50
120 132x25
121 132x43
122 132x50
123 132x60