
Open terminal from App Launcher or via Ctrl+Alt+T keys. You can obtain the latest GRUB source from the GIT: Install GRUB v2 (but don't remove the grub 1 yet). In the grub menu, if you can't find the Windows 10 boot, loader then select the advanced option (which is just below Ubuntu option in Grub menu) and press "Enter" and then run Ubuntu in recovery mode. I already did everything suggested in other questions but no luck.

(Optional) When you see the dialog at "Finish This tutorial shows how you can upgrade your GRUB bootloader to GRUB 2 on Ubuntu 9. Open your Ubuntu command line, the Terminal, either through the system Dash or the Ctrl+Alt+T shortcut. In order to install GRUB under a UNIX-like OS (such as GNU), invoke the program grub-install (see Invoking grub-install) as the superuser (root).

Automatically generates config files for PhoenixOS, Android, Ubuntu, Debian, Suse, Fedora, Manjaro, Mint, Clover and Windows. With it, you can set the default OS, add/remove boot entries, change boot order, set an background image, and more.

Mount the partition where your Ubuntu is installed. Install grub ubuntu Now to install Grub Customizer, run the following command: $ sudo apt-get install grub-customizer.
