grub2 - Dual-boot boot menu does not show up after installing Ubuntu 15.10 alongside Windows 10

I have installed Ubuntu 15.10 alongside Windows 10 with UEFI. To install Ubuntu, I chose the option install alongside Windows 10 or something similar to this. Then I created a new partition for Ubuntu and installed it. After installation, the boot menu did not show up. Initially I thought Ubuntu has not been installed, but when I plugged in the USB drive and wanted to install Ubuntu I saw an option of reinstalling Ubuntu on my machine. So, I found out that Ubuntu is installed. Pressing F8 and F12 also does not help.

Can anyone help me bring up the GRUB boot menu?

In Windows, I also entered the command bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi in cmd, but still the boot menu does not show up.

1. On Windows 10, go to the start menu.




2. Search and open Recovery Options. The description for it should say System settings.




3. Under Advanced startup click Restart now.




4. Click Use a device; it's description should say
   "Use a USB drive, network connection, or Windows recovery DVD".




5. Click Ubuntu and hopefully it should take you to the grub boot menu.




6. Next try going back to the live Ubuntu session on the USB to reinstall grub-efi. On the live session, open a terminal and enter the following commands in:

   
   
   

   
   

   sudo mount /dev/sda# /mnt
   
   

   
   
   

   Replace the hashtag in /dev/sda# with the number representing the partition where you had Ubuntu installed. You can check using gnome-disks or gparted.

   
   
   

   sudo mount /dev/sda# /mnt/boot/efi
   

   
   
   

   Replace the hashtag in /dev/sda# with the number representing the EFI partition. It's usually /dev/sda2.

   
   
   

   sudo mount -o bind /dev /mnt/dev
   
   sudo mount -o bind /proc /mnt/proc
   sudo mount -o bind /sys /mnt/sys
   sudo mount -o bind /run /mnt/run
   sudo chroot /mnt/
   sudo apt-get install --reinstall grub-efi
   sudo update-grub
   

   
   
   

   Reboot.

   
   





7. If that fails, go to your BIOS settings with one of the F keys; that option might be Enter setup. Look for boot option priorities and move Ubuntu above the Windows Boot Manager. Go to the option to save the changes then reboot.




8. Lastly you can try using Boot-Repair.