: Select Repair your computer > Troubleshoot > Advanced options > Command Prompt .
This is the most direct method and doesn't require downloading extra software if you have a Windows installation or recovery USB.
: Type these commands in order, pressing Enter after each: Hard Drive Mbr Repair Software
: Insert your Windows installation USB/DVD and boot from it.
If your computer refuses to boot or displays errors like "Operating System not found," a damaged Master Boot Record (MBR) is often the culprit. You can fix this using built-in Windows tools or dedicated third-party software. : Select Repair your computer > Troubleshoot >
bootrec /rebuildbcd — Scans for installations and rebuilds the Boot Configuration Data. How Do I Fix the Master Boot Record (MBR)?
bootrec /fixmbr — Writes a new Windows-compatible MBR to the system partition. If your computer refuses to boot or displays
bootrec /fixboot — Writes a new boot sector to the partition.