Fix an operating system wasn't found

If you see the “Operating System not found” boot error message on your computer, it means that no operating system bootloader has been found on the current disk. So, your computer cannot find & start the Windows bootloader (or the bootloader of any other OS installed on your computer).

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An error you see when trying to lớn boot an OS may also look lượt thích this:

An operating system wasn"t found. Try disconnecting any drives that don"t contain an operating system. Press Ctrl+Alt+Del lớn restart.


The same error on Lenovo computers or laptops says the following:

Error 1962: No operating system found. Boot sequence will automatically repeat.


Comtháng Reasons of “Operating System not Found” Error

The most comtháng reasons why an OS cannot boot with the “Operating system not found” error are:

A damaged system partition, missing or damaged MBR (master boot record), no active sầu partition (or an incorrect disk partition is marked as active);A corrupted boot configuration data (BCD);An HDD with the installed OS is not connected (it may include such problems as poor ribbon cable connection, any hardware issues with the drive, RAID or disk controller).


First of all make sure that:

Your hard drive with the OS is connected lớn your computer (disconnect all other drives and USB devices: this is what you are advised khổng lồ vì in the first screenshot);nguồn & ribbon cables are connected properly;The hard drive sầu is detected in the BIOS/UEFI of your computer. Make it the primary boot device;Check the Secure Boot settings in UEFI. They may have been changed (check if Windows is booted with the Secure Boot mode enabled/disabled và in the Legacy mode).

If you did everything described above, and your Windows still doesn’t boot, you will have sầu lớn restore the Windows bootloader & disk boot record.

Identify Disk Partition Table & Windows Partition

In order to lớn repair your bootloader, you will need a Windows install truyền thông media (on a CD/DVD/ bootable USB drive) or rescue disk with the same OS version you have sầu installed on your drive (or newer).

Change the boot order in BIOS (UEFI), boot from your installation/rescue disk và run the comm& prompt (if you are using Windows 10 install truyền thông, press Shift+F10 on the language selection screen).


First of all, you must detect the type of the partition table on your disk: GPT or MBR. The method for restoring the Windows bootloader depends on it.Run:diskpartEnter this command: danh mục diskIf there is an asterisk (*) in the Gpt column for your disk, than the GPT partition table is used, otherwise it is MBR.


Display the list of volumes on the disk:

menu vol


Exit the diskpart session:exitJudging by the disk kích cỡ, Windows is likely to lớn be installed on E: drive. Cheông xã it by running this command:dir e:

As you can see, there are Windows, Program Files, Users & other standard folders on the drive sầu.


So we have detected the disk layout type & the drive letter of the disk Windows is installed on. Depending on the disk partition table you have, go khổng lồ the corresponding section of this article.

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How lớn Repair the Windows Bootloader on the MBR Disk?

We suppose that your computer is using BIOS và the disk partition table is MBR.

Here is a detailed article on “How to Rebuild BCD File & MBR on a BIOS-based computer?”.

Create bootloader configuration files on the E: drive:

bcdboot E:Windows /S E:

The “Boot files successfully created” message will appear.


Re-create a Master Boot Record (MBR):

bootrec.exe pháo /FixMbrbootrec.exe pháo /FixBootbootrec.exe cộ /RebuildBcd

Make your Windows partition active sầu (BIOS transfers control to the OS bootloader on the active MBR partition):

In this article we don’t show how to lớn re-create the System Reserved partition, since you can place the bootmgr on a drive with Windows installed.

diskpartdanh sách disksel disk 0list volselect volume 2 (earlier we detected that Windows is installed on this volume)activeexit


Restart your computer và make sure that Windows has booted correctly và the “Operating system not found” error has not appeared.

How to Repair the EFI Bootloader on a GPT Disk of UEFI Computer?

If your disk has the GPT partition layout, it means that your computer is using the UEFI architecture instead of BIOS. You can find the complete guide on how to restore Windows 10 bootloader on a UEFI-based computer in the following article: How lớn Repair Windows 10 UEFI Bootloader? Let’s consider the main steps in brief.

First of all, find a FAT32 hidden partition & assign a drive letter khổng lồ it (the size of this partition is 100-300MB, it is used to lớn store the Windows bootloader which is called by the EFI bootloader).

DiskpartList vol

For example, you have sầu detected that it is Volume 1 with the label BOOTSTRAPhường.


Select this EFI partition and assign a drive letter to lớn it:

select volume 2assign letter M:exit

Re-create the BCD bootloader configuration file:

cd /d m:efimicrosoftoot en BCD BCD.bakbcdboot E:Windows /l en-us /s M: /f ALL

The E:Windows path is used, since earlier we detected that in this example Windows was installed on E: drive.

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Reboot your computer, remove the boot truyền thông (USB flash drive) và make sure that Windows has booted correctly.

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