Missing Operating System

When power on your PC, sometimes you receive a black screen with an error message that reads “Missing operating system”. How does this happen? How can you remove this error and boot Windows normally? Just find the answers in this post.
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Tip: sometimes this error message is shown as “Operating system not found”, both of them means the same thing and has the same solutions.

Causes for Missing Operating System Not Found

Usually, there are 5 common causes for this issue:
1) The BIOS does not detect the hard disk drive that installs Windows.
2) The hard disk failed either physically or logically.
3) The computer is trying to boot from other devices.
4) Master Boot Record (MBR) located on the hard drive is damaged or corrupted.
5) The active partition is set wrong.
If any of the 5 causes are true, missing operating system can occur.

How to Fix Missing Operating System Windows 10/8/7

Way 1. Check if the system disk is detected in BIOS
Start your PC and press some key to enter BIOS. The key can be different from computers and you may need to confirm on internet. In BIOS please find these or similar items: IDE Primary Master, IDE Primary Slave, IDE Secondary Master, etc.
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If no disk is shown up or the system disk isn’t here, we can say BIOS doesn’t detect the drive. At this time, reconnect the hard drive and check. If this does not help, you may get a failing hard drive. At this time, you should first of all consider transferring data off the drive before you tale the next step. Read How Do I Clone Hard Drive in Windows 7 32/64 Bit to know more.
Way 2. Set BIOS to default state
Wrong BIOS setting can also bring missing operating system issue. To verify, just do the followings:
Restart computer and enter BIOS. Find and enable the default setup option, which could beone of these: Load Optimal Defaults, Get Default Values, Load Optimized Defaults, Load Setup Defaults, and so on. Press on F10 to save changes and quite from BIOS.
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Now restart your PC. If the error persists, try way 3.
Way 3. Rebuild MBR
To rebuild MBR, you will need the help of Windows installation disc or a third-party bootable partition manager. Take the former one for example:
Select “Repair my computer” instead of ”Install now”, then in system recovery options page, enter command prompt.
Now type these commands one by one and each of them should be ended up with the Enter key.
bootrec /fixmbr
bootrec /fixboot
bootrec /rebuildbcd
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Exit Windows installation disk and boot your PC again.
Way 4. Check active partition
If all of the three ways does nothing to help, you can use MiniTool Partition Wizard Bootable to check and set the correct partition active. For more information, read 5 Perfect Solutions to Getting Missing Operating System Back.
Now we have gone through all the suggestion to fixing missing operating system issue. We hope they are helpful and you never try the last one.


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