Rescue Grub Menu part 1 Installing Super Grub2 Disk Iso
https://www.supergrubdisk.org/wizard-...
(in Terminal):
1./ sudo apt-get install grub2
I chose YES and next between few positions, I chose main, whole disc dev/sda (not sda1, sda6 or others but main 'dev/sda')
2./ sudo upgrade-from-grub-legacy
3./ reboot
part 2 • How To Rescue Grub part 2
GNU GRUB is a boot loader package from the GNU Project. GRUB is the reference implementation of the Free Software Foundation's Multiboot Specification, which provides a user the choice to boot one of ... Wikipedia
Operating system: Linux, macOS, BSD, Solaris (x86 port) and Windows (through chainloading)
Stable release: 2.02 (GRUB 2) / April 26, 2017; 21 months ago
Preview release: 2.02~rc2 (GRUB 2) / March 15, 2017; 22 months ago
Developed by: GNU Project
Platforms: x86-32 (32 bit Intel x86), x86-64, IA-64, ARM architecture, PowerPC, MIPS architecture, SPARC
Written in: Assembly language, C