Users may on rare occasions receive Missing Operating System, Operating System Not Found or No operating system found error screen while booting their Windows computer. If you frequently get these messages while booting Windows 10/8/7/Vista, then this post will guide you in the proper direction.
Missing Operating System Not Found
In most cases, this happens when you install Windows Vista or later operating systems in conjunction with older operating systems. For example, Windows XP used Boot.ini and Vista onwards it was BCD Edit.exe located in the Windows\System32 folder. There can be two scenarios here.
First, you install Windows XP or prior operating systems and then install Windows 10. In this case, the BCD Editor may take over and remove boot.ini. This makes the computer believe that there is only one operating system installed and that is Windows 10. Such issues can be fixed by running BCD Editor (Boot Configuration Data Editor).
Maybe you installed Windows 10 first, and then you went on to install Windows XP. The boot loader of Windows XP is made default, and you won’t find Windows 10 in the list of operating systems. In worst case scenario, you won’t find any operating system as the boot loader is corrupt due to conflict of both boot.ini and BCD.exe. This situation too can be fixed using BCD Editor. You just need to know how to add the operating systems to the boot loader and most importantly, assign them each, a different drive letter.
You will need to boot with the disk, and repair Windows.
Here is what you can try. Boot the Windows Installation Media, choose Repair and then Open a Command Prompt window. In Windows 10 you can also access the Command Prompt via Advanced Startup Options.
Now enter the following commands one after the other and hit Enter after each:
Anand Khanse is the Admin of TheWindowsClub.com, a 10-year Microsoft MVP Awardee in Windows (2006-16) & a Windows Insider MVP since then. Please read the entire post & the comments first, create a System Restore Point before making any changes to your system & be careful about any 3rd-party offers while installing freeware.