Boot loader vanished!

I had set up a dual boot with windows 10 and CL on my pc. yesterday I had a PSU malfunction. however, I replaced it. after booting the pc I wasn’t greeted with the familiar dual boot screen. I even tried booting CL from the bios apparently CL is missing from possible boot listing too. I boot into windows again and checked the disc partition. luckily CL partition is still there. Now my question is how can I enable dual-booting screen/ grub boot loader again? what caused this issue?

thanks in advance.

the tutorial site has information on dual-boot with Windows. Follow the part on installing CL after Windows, and you can restore it.