What to do if Windows 10 is completely corrupted and unusable
If you have a PC without a Windows 10 installation or if your current Windows 10 installation has become corrupted and is unable to repair itself then you will need to undertake a new installation from scratch.
In order to do this, you will require a Windows 10 installation USB drive or a Windows 10 recovery drive. If you don't have one of these, you can create one but you will need another working Windows 10 PC to do so. the instructions for creating the USB drive are in this video: https://www.youtube.com/watch?v=3Sqek5J_EOg
Once you have created the USB drive, insert it into the PC which won't boot and choose to boot from the USB drive instead of the built in SSD in the PC. This next video shows you how to install it. If the PC tries to boot from the internal SSD, you may need to change the boot order in the system BIOS https://www.youtube.com/watch?v=ozPALCmt-e0