Grub not recognizing windows 10

For whatever reason (probably due to updating and Windows 10 using a different boot method or something akin to that) the listing of available operating systems has gone missing. This is something that can be fixed in a number of different ways. The simplest one to try is this:

• Open the terminal by pressing CTRL+ALT+T.

• Enter this command:

  sudo update-grub

• Press the ENTER button.

• Enter your password (no asterisks will show, nothing will change on the screen, the cursor will not move, this is normal).
• Press the ENTER button.

• Let the system do its stuff and then enter this command:

  sudo reboot

This will allow grub to automatically find and enumerate the available operating systems and then give you the option to boot to the desired operating system during the boot process.