Grub won't start, how to fix?

Question

ubuntu

There was Windows 7. Put parallel to Ubuntu.
But I created a partition, and installed a hornbeam on this uefi-boot partition (I'm not sure if it's true or not) and installed the bootloader there during installation
As a result, now when you turn on the computer, Ubuntu starts up, there is no system selection (

Answer 1

grub is worth it, since it loads the system.
Simply, I think, it is necessary to register the section with Windows in the config with handles, then there will be a choice of OS.
Config here:
/boot/grub/grub.cnf
But there is a risk of breaking it, make backups.
Or reinstall grub to a different partition from the boot drive.