Of all the bugs, glitches, and problems that can arise while using Windows 10, few create as much fear as the dreaded "Operating System Not Found" screen. Visions of the loss of your entire media collection, your work and your precious photos flash before your eyes.

To stop. Take a deep breath. Your data is still there – and just as important is that you can fix it. Let's see how to fix "Operating System Not Found" error on Windows 10.

1. Check the BIOS

You need to look for two things in the BIOS. First of all, you need to make sure that your computer recognizes your hard drive. Second, you need to make sure that the drive you installed Windows on is listed as the preferred startup drive.

The method for entering the BIOS varies from manufacturer to manufacturer. Usually you have to push escape, Extinguish, or one of the Function keys during the boot process before Windows loads. You should see a message on the screen during the startup process letting you know which key is correct.

The BIOS menu itself also varies between devices. On the whole, you have to Boots Tab at the top of the screen. Unfortunately, you can only use your keyboard to navigate the BIOS menu, so keep an eye out for a list of controls on the BIOS screen.

On the Boot tab, highlight hard disk and press Enter. Make sure hard disk is listed above USB storage, CD DVD BD-ROM, Removable media, and Network start. You can adjust the order with the + and Key.

If everything was OK in your BIOS menu, skip to step 3. If the hard drive is not listed, go to step 2.

2. Reset the BIOS

If your computer does not recognize your hard drive, there are many possible causes. For the non-tech-savvy user, the only easy solution is to reset the entire BIOS menu to its default values.

At the bottom of the BIOS menu you should see a key for see Set up default settings or Reset BIOS. On some machines it is F9, but it could be different with you. Confirm your decision when prompted and restart your computer.

If the operating system is still not found, you will no longer be able to read this article. Unless you know much about building computers, you will need to take your computer to a computer repair shop.

3. Repair the boot records

Microsoft Windows primarily relies on three sets of data to start your computer. You are the Master Boot Record (MBR), DOS boot record (DBR) and the Boot configuration database (BCD).

If any of the three records become corrupted or damaged, there is a high chance that an "Operating system not found" message will appear.

Fortunately, repairing these records isn't as complicated as you might think. All you need is a removable Windows installation drive. Use Microsoft's Media Creation Tool to create some Windows 10 installation media.

When your tool is ready, you'll need to use it to boot your computer. Depending on your device, you may only have to press a single key during the boot process or change the boot order in the BIOS menu.

Finally, you will see the Windows setup screen. Enter your preferred language, keyboard and time format and click Next. Select on the next screen Repair your computer.

Next, navigate to Troubleshoot> Advanced Options> Command Prompt. When the command prompt loads, enter the following three commands. Press Enter after each of them:

  • bootrec.exe / fixmbr
  • bootrec.exe / fixboot
  • bootrec.exe / rebuildbcd

Each command can take a few minutes. Once all processes are done, restart your PC and see if it starts up successfully.

4. Enable or disable UEFI Secure Boot

Almost every Windows computer is delivered with UEFI firmware and activated Secure Boot. However, in some cases, it may not work. For example, if Windows is installed on a GUID partition table, it can only start in UEFI mode. Conversely, if Windows 10 is running on an MBR disk, it cannot start in UEFI mode.

So it is advisable to either enable or disable UEFI Secure Boot and see if it makes a difference. You make the adjustments in the BIOS menu. Usually the option is called Safe start-up and can be found in security Tab.

5. Activate the Windows partition

The Windows partition may be disabled. You can fix this using Windows' native Diskpart tool. In order to work through the following steps, you need a Windows installation medium USB again.

Related: How to Use DiskPart to Partition Your Hard Drive

Turn on your computer and boot from the tool. As in step 3, you need to enter your language preferences etc, click on Next, to choose Repair your computer, and go to Troubleshoot> Advanced Options> Command Prompt.

At the command prompt, enter Diskpart and press Enter, then type List of data carriers and press Enter. You will see a list of all the hard drives connected to your computer. Make a note of the disk number required. Usually it's the biggest.

Next, enter Select data carrier (number), where (number) is replaced by the above number. Press Enter.

Enter now List volume and press Enter. It will show you all the partitions on the selected hard drive. Find out which partition Windows is installed on and write down the number, then enter choose volume (number), and replace (number) with the number you just wrote down.

Finally enter active and press Enter. To see if the process was successful, restart your computer.

6. Use Easy Recovery Essentials

Easy Recovery Essentials is a third party app that specializes in troubleshooting boot problems. If none of the previous five steps worked, it's worth trying.

In addition to resolving the "Operating System Not Found" message, other common startup error messages can also be resolved. They include:

  • INACCESSIBLE_BOOT_DEVICE.

  • INACCESSIBLE_BOOT_VOLUME.

  • UNMOUNTABLE_BOOT_VOLUME.

  • Bootmgr is missing.

  • The boot configuration data for your PC is missing or contains errors.

  • An error occurred while trying to read the boot configuration data.

  • Boot.ini not found.

  • … and more.

Just download the app, burn the ISO to a CD, and use the CD to boot your computer. The app's wizard will guide you through the repair process.

Download: Easy Recovery Basics ($ 30)

Last resort: go to the shops

Our tips should help you resolve Windows 10 Operating System Not Found error in all but worst cases. Unfortunately, however, this is just one of many error messages that you are likely to encounter while using the Microsoft operating system.

If you can't figure out what's wrong with your machine, there's little point in fiddling around. If you're not tech savvy, you can do more harm than good. As a last resort, go to your local pc repair facility and they should be able to get you up and running in no time.

Get Windows working again

Whether you're fixing the problem yourself or need professional help, hopefully you get a PC that remembers it has an operating system. Best of all, your files should all be safe and sound!

Microsoft Windows itself is full of potential bugs, and the official store is no different. However, there are ways to troubleshoot problems you encounter with the Microsoft Store.

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About the author

Dan price
(1574 articles published)

Dan joined MakeUseOf in 2014 and has been Partnerships Director since July 2020. Contact him with any questions about sponsored content, affiliate agreements, promotions, and other forms of partnership. You can also find him in the showroom every year at CES in Las Vegas. Say hello when you come with me. Prior to his writing career, he was a financial advisor.

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