Overview of Missing Operating System Issue

 
While trying to boot your computer, perhaps you can find the PC is unbootable, and an error message like “Missing operating system” or “Operating System not found” appears on your computer screen, just like the figure shows:
 

 
When suffering from this problem, you are not allowed to access Windows 10/8/7. Then, you want to know the causes for this issue and the solutions to it. To be specific, there are five factors, for example, Windows Master Boot Record (MBR) is damaged, the system partition holding boot files is not active, BIOS settings are not correct, the hard drive is damaged, BIOS doesn’t detect the installation disc. Depending on different reasons, the solutions are also different. So, just figure out which situation your computer faces and try the relative way.
 

How to Fix Missing Operating System?

Way 1: Repair Master Boot Record (MBR)

 
Damaged MBR is one main factor of operating system not found error. Thus, to repair MBR is an important thing. How to perform this repair? One is to repair corrupted MBR with a Windows installation disc. Please boot your PC from this disc and then open Command Prompt to type these commands: “bootrec /fixmbr” and “bootrec /fixboot“.
 
Or you can use a third-party partition manager – MiniTool Partition Wizard Professional Edition. Just use this software to create a bootable disc to boot your PC and then click “Rebuild MBR” to repair damaged MBR to fix no operating system found issue.
 

 

Way 2: Set Correct Partition Active

 
Under Legacy BIOS + MBR mode, Windows boot partition or system partition must be set active so that Windows can be booted. If you set an incorrect partition active, missing operating system issue will happen. So, please boot your PC with MiniTool Partition Wizard bootable disc and then click “Set Active” in the action panel.
 

 

Way 3: Set BIOS to Default Settings

 
Improper or incorrect BIOS setting can also cause no operating system found issue. In this case, you can choose to set BIOS to its default status to fix this issue. Please restart your PC and enter BIOS, enable the default setup option, for instance, Load Optimized Defaults, Load Optimal Defaults, Load Setup Defaults, Get Default Values, and more.
 

 

Way 4: Test Hard Drive

 
As to some types of motherboards, a hard drive diagnostic tool is added and it can be used to test hard drive errors. Here take an HP laptop as an example.
 
1. Press Power button and hold F10 to turn on your PC. After the screen shows you with the test, release F10.
2. Select “Tools” in “BIOS Setup Utility”.
3. Select “Hard Drive Self Test”.
 

 
If no errors are found, try another way. If your hard drive gets damaged, please use MiniTool Partition Wizard to copy all partition to another hard drive and wipe the damaged disk.
 

Way 5: Check Whether the Hard Drive Is Detected by Windows

 
In “BIOS Setup Utility” interface, please find IDE Primary Master, IDE Primary Slave, IDE Secondary Master and check whether they can be detected or not. If they show “None” or “Not Detected“, it means your disk is not detected. Please reconnect the disk again.
 
Until now, five ways are told you simply. If you need to learn more details about each solution, please go to this post – 5 Perfect Solutions to Getting Missing Operating System Back.