Original post : How To Reinstall Windows 10.
A Windows 10 setup USB or DVD is required for these instructions!
If you do not have access to the Windows 10 setup USB or DVD, you cannot follow the instructions below. You can still try using our free Windows 10 recovery CDs to fix your Windows 10 PC and repair startup issues and system problems.
You must be able to boot into Windows 10 to follow these instructions!
If you cannot boot into Windows 10, you cannot perform a safe repair install of Windows. If you are unable to boot into Windows, you will first need to repair Windows 10 boot issues by using a recovery CD like EasyRE for Windows to fix your Windows startup and log in to your PC before following the instructions below!