Fix Windows 10 Missing operating system error

I applied the free upgrade to Windows 10 on my computer. After the installer got to around 90% and made a rebooting, the BIOS screen appeared with Missing operating system error. That prevented me from booting back in Windows and actually turn the device to be unusable completely.

A number of users get the Missing operating system or operating System Not Found error during the upgrading process of Windows 10. That may be caused by those reasons , such as corrupted Hard disk,hard disk is not detected by BIOS, or your system partition is not active. You could try the method to fix the issues.
Note: This process is very safe, so any type of data through this process won’t be deleted.
* First you need to find your bootable cd/DVD or create Bootable USB stick.
You can download the Windows USB/DVD Download Tool and run it to make one copy of the ISO file on USB flash drive, or other media by following instruction here.
* Power up your PC and press F2 or delete button from your keyboard to enter the BIOS setting, and set it up to boot from CD or USB.
* Attach the Bootable USB or DVD in your tablet or computer, and make a re-booting.
* Under the Install Now button., you should see the Repair Your Computer. Click on it. You might select your OS from list if needed.
* Open CMD (Command Prompt) in Repair Your Computer screen.
* Type those command and press Enter to execute it.
Bootrec /fixmbr
* Then repeat the same way for running this command:
Bootrec /fixboot
* Finally remove your cd or USB stick and reboot to check if it is fine

If it is still not working, open the Command Prompt again by the above method,
* Type diskpart to execute it, then type list volume to display all volumes.
* Find your system volume number where the Windows is installed.
* Input the command and press Enter:
select volume ***
For example, select volume 3
* Input ACTIVE to active your system partition.
* Then input exit to close cmd and restart the device.


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