there was one time that I used a program to modifying UEFI boot loader,

but accidentally removed default boot loader of win10,

then I surfed the internet for resolution,

but failed because Microsoft's variety of versions

finally, I found it.

https://thinker-evans.blogspot.com/2020/02/windows-10-uefi-bootloaderwindows-10.html

Here's the point:

After Windows 10 1709, bootrec /fixboot is deprecated.
 

step 1: build usb booting image for windows recovery

step 2: mount usb rod for recovery

step 3: >bcdboot "C:\Windows" /s Z: /f UEFI /l zh-tw

Modify disk code for your situation