Windows system not recognized anymore

Hello, here's the situation :

I have two hard drives : C and H.
The C drive used to be my main drive containing the system. One year ago, I installed Windows on my second H drive and placed all the contents of the C drive in the trash and cleared it (some could not be removed due to lack of authorization, namely 3 folders : programs, program data, program files (x86)).
It has been working fine ever since.

When cleaning up my system yesterday, I decided to finally remove these 3 folders from the C drive. I boot up the computer from a Windows 10 installer on a USB drive and went in the command prompt to execute DISKPART and clear the C drive altogether.

When rebooting, I had the "bootmgr is missing" message, even when disconnecting the C drive from my motherboard's SATA port.

I reinstalled Windows 10 on the C drive and checked the H drive : all my data is still here, *including the system*.

Strange thing is, the latter is not recognized my either the bios ("An operating system wasn't found [...] ") or the msconfig window.


Any idea on why this was caused and how to get my initial system on H drive back up and running ?

Thanks a lot for reading and taking the time to answer !

Your system partition and boot files were on the drive that you wiped with the diskpart command.

You need to establish the boot files onto the other hard drive. The way you do that depends on if you have legacy BIOS or UEFI.

Thank you for your response, I have UEFI, my motherboard is an Asus P8Z68-V gen 3.

I tried to create a 500Mo EFI partition with diskpart on the H drive, but I couldn't since it is not GPR.

Thank you for your response. I have UEFI, my motherboard is an Asus P8Z68-V gen 3.

EDIT: sorry for the double post, did not realise there was supposed to be a delay.

The easiest way to fix your problem is going to be to make an image of the Windows partition on the "H" drive using a program such as Macrium Reflect. Store the image on the other HDD in the system. Then wipe the hard drive with Windows on it completely, and do a clean install of Windows to it. That should set up the drive with GPT partitioning and UEFI booting. Then you will boot from the Macrium Reflect rescue drive and restore the image of the original Windows partition only over the top of the clean install Windows, run the utility to Fix Windows boot problems included on the Macrium Rescue Drive.

That should set everything right.