Where and how to use windows boot intercept?

Good day! I have big problems with this Windows 8 OS. My windows 8 OS was corrupted in an unknown reason. So I ask my friend if there is a way to repair it? But he only told me that I need to intercept the boot process. But the problem is I can’t find the BCD. So guys, where is the windows boot intercept? How to use it properly? Thanks.
