7 + Fixes: Missing Operating System or Operating System Not Found

The "missing operating system" or "operating system not found" error typically appears on a black screen when you start up a Windows computer. It prevents you from booting into Windows. This error is quite common on Dell, Acer, Lenovo, HP, and Sony desktops and laptops. You can keep reading to learn more about the error, or jump straight to the solutions.

?Also Read: How to Fix Total Identified Windows Installations 0

Causes of "Missing Operating System" or "Operating System Not Found"

Typically, issues with the BIOS setup, hard drive condition, or the Master Boot Record (MBR) can prevent Windows from booting and result in the two aforementioned error messages. Here are some specific reasons that can cause "Operating System Not Found":

1. The Basic Input/Output System (BIOS) does not detect the hard disk. 2. The hard disk drive is damaged. 3. Improper/incorrect BIOS settings. 4. Windows Master Boot Record (MBR) is corrupt/damaged. 5. An incompatible partition is set as active.

Note: If the BIOS does not detect the operating system, you will see one of the following error messages, which indicate the same problem on different operating system versions.

Error message 1: Missing Operating System

Error message 2: Operating system not found

Missing Operating System

So how can you eliminate this error and get your computer to detect the operating system and boot up successfully again? That's what we aim to assist with in the upcoming section. Keep reading, and you'll find solutions to instantly fix the "Operating System Not Found" error.

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7 Solutions to Fix Missing Operating System or Operating System Not Found Error

Now that you're aware of the reasons behind the "Operating System Not Found" or "Missing Operating System" error in Windows, it's time to apply effective solutions to recover the missing OS. Don't forget to share this article to inform others about the causes of this issue.

Solution 1: Check if the Hard Drive Is Detected by BIOS

When you encounter "non-system disk or disk error" on your computer, the BIOS configuration will fail to detect and load the operating system, preventing your computer from starting up. In such a situation, you should first check the BIOS settings to ensure that the OS (operating system) hard drive is set as the Boot device. Follow these detailed steps:

Step 1: Press and hold "F12/F10" while pressing the "Power" button to turn on the PC.

Step 2: Release F12/F10 when the BIOS Setup Utility is displayed.

Step 3: Try to locate the IDE Primary Master, IDE Primary Slave, and IDE Secondary Master, and check if they are detected or not.

Fix operating system not found error.

For more solutions, you can refer to this page to fix the hard disk not detected in BIOS issue successfully.

If no disk is shown or displayed as None/Not Detected, it means that the BIOS doesn't recognize the drive. In this case, you can select None and then choose Auto. This might resolve the "Operating System not found" error.

If the system disk information is displayed, it means that the BIOS can detect the hard drive, and you need to exit the BIOS.

Solution 2: Test Hard Drive Issues

The next step is to check if the operating system (OS) hard drive has any issues or errors in the BIOS settings. Follow these steps to learn how to do it yourself:

Step 1: Press and hold "F10" and then press the "Power" button to turn on the PC > Release "F10" once the PC screen displays a test.

Step 2: Use the right arrow to select the "Tools" menu in the BIOS Setup Utility.

Step 3: Select "Hard Drive Self Test," and then press "Enter" to start the test.

After the test, you'll receive two results:

#1. All Tests Passed

This means the hard drive is not damaged. You may proceed to Solution 3 to reset BIOS to default in order to resolve the missing operating system issue.

#2. The Test Failed

As long as these devices are under warranty, you should contact your hard disk or computer manufacturer to obtain a replacement.

Solution 3: Set the BIOS to default settings

Improper configurations or incorrect BIOS settings can also trigger the 'Operating System Not Found' issue on your PC. You can attempt to reset the BIOS to its default settings to address this problem.

Step 1: Restart your PC and enter BIOS.

Step 2: Look for the BIOS option to load the default settings, which might be called something like Load Optimal Defaults, Get Default Values, Load Optimized Defaults, Load Setup Defaults, or similar.

Step 3: Press "F10" to save the changes and exit from BIOS.

If this method does not work, the MBR disk might be damaged, and you can jump to Solution 4 to fix MBR Windows 10 or a newer operating system with a professional MBR repair method.

Further Reading: Windows 11 Black Screen with Cursor

Solution 4: Repair MBR with the Installation CD/DVD

Both incorrect operations and virus infections can damage the MBR, which is located in the first sector – usually sector 0 – of the hard drive. This will prevent Windows from booting. You can attempt to repair the MBR using the Windows installation disc in Command Prompt.

Insert the Windows Operating System disc into the optical (CD/DVD) drive

Step 1: Press the "Power" button to turn on the PC > Hit "Enter" when prompted to Boot from CD.

Step 2: Press the "R" key in the Windows Setup menu to launch the Recovery Console.

Step 3: Type: FIXMBR at the C:\> prompt and press [Enter].

Step 4: Press the "Y" key and then press "Enter" when prompted to write a new MBR.

Step 5: Press the "Power" button to restart your PC when the MBR finishes the writing process.

Solution 5: Rebuild MBR without Windows Installation CD/DVD

If you prefer an easier and safer way to rebuild or repair the MBR disk, you may apply third-party partition magic software - AOMEI Partition Assistant to perform an automatic repair.

Boot your Windows from the WinPE environment you created, and start repairing the MBR with just a few clicks.

Step 1. Create a WinPE bootable disk

1. Launch tools Partition Master, and click "Bootable Media" on the toolbar. Select "Create bootable media". 2. Click "Next" to complete the process.

Step 2. Boot the Tools Partition Master Bootable USB

Connect the bootable USB or CD/DVD to your PC. Press F2 or Del when you restart the computer to enter the BIOS screen. Set and boot your computer from "Removable Devices" or "CD-ROM Drive". Then, the Partition Master tool will run automatically.

Step 3. Rebuild MBR

Click "Toolkit" and select "Rebuild MBR".

Rebuild MBR

Select the disk and the type of MBR, then click "Rebuild".

After that, you can see "MBR has been successfully rebuilt on Disk X".

Solution 6: Repair MBR for HP

Solutions 4 and 5 for repairing a corrupted MBR apply to various computer and laptop brands. Moreover, some brands offer built-in tools to address MBR issues. For instance, the Windows Operating System Disc (OSD) included with an HP notebook PC can be utilized to repair the Master Boot Record.

Follow all the steps provided at: https://support.hp.com/us-en/document/c00476274

Solution 7: Set the Correct Partition Active

When Windows is running in Legacy BIOS + MBR mode, the boot partition/system partition needs to be marked as active so that the Master Boot Record (MBR) can pass the boot process to the boot manager and locate Windows. If the system partition or boot partition is not set as active, you might encounter the "operating system not found" error.

In the same partition tool, create the Partition Master Bootable USB first, and follow the steps to set the boot partition active:

Step 1. Run the partition manager software. On the disk map, right-click the target partition and choose "Advanced".

Step 2. Next, select "Set Active" from the dropdown menu. Click "Yes." Then choose "Execute 1 Task(s)" and click "Apply."

Conclusion

All effective solutions to the "Missing Operating System" or "Operating System not found" error are meticulously presented on this page. You may attempt any of the methods to rectify the issue and restore a functional Windows system, enabling you to resume using your computer normally.

As long as you set a healthy hard drive as the boot drive that can be detected by the BIOS settings, the computer should be able to find and load your OS from the boot drive successfully. If issues arise with a malfunctioning MBR table or if the OS partition is not set as active, you can turn to tools like Partition Master for assistance.

Frequently Asked Questions About Missing Operating Systems or "Operating System Not Found"

If you still have doubts about this issue, relax and follow the quick answers to each question as listed below.

< strong >1. Why is my PC showing missing operating systems?

The reasons for a missing operating system on a Windows computer can be varied, including the OS drive not being detected by the BIOS, incorrect BIOS settings, MBR corruption, the OS drive not being set as active, and so on.

< strong > 2. What is missing from the Windows 10 operating system? < /strong >

The "Missing Operating System" error is a system issue that affects most operating systems, including Windows 10/11 as well as older versions like Windows 8.1/8/7/Vista. When this error occurs, your computer fails to fully boot from the operating system drive. Instead, you'll encounter a black screen displaying error messages such as "Missing Operating System..." or "Operating System not found...". The problem will persist unless you apply the appropriate solutions.

3. How do I fix a missing operating system in Windows 10/7?

Based on the solutions offered on this page, you can effectively resolve the "missing operating system" error on Windows 10 or Windows 7 computers by attempting to reset BIOS settings to default, repairing a corrupted MBR partition table, and setting the OS drive as active, among other methods. For more detailed instructions, refer to the respective solutions provided on this page for assistance.