Method 3: Set Linux boot for EFI from Windows (last resort)
Warning!
Playing with your boot settings can leave your system messed up. I advise having a recovery disk or Windows installation disk with you to reverse boot settings. Keeping the Linux live USB can also help in many situations.
Step 1
In Windows, go to the menu.
Access Menu in Windows 10
Step 2
Search for Command Prompt, right click on it to run it as administrator.
Command Prompt in Windows 10
Step 3
This is strictly for Ubuntu. Other distributions might have some other folder name.
In here, copy and paste the command below:
bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi
You don’t need to enter a password or anything like that. The command should run just fine given that your account has admin rights.
Step 4
Restart and you’ll be welcomed by the familiar Grub screen. I hope this quick tutorial helped you fix the Grub issue.