
It is possible that you have to change the boot order in your BIOS to boot from DVD.
Start your problematic PC, insert your Windows DVD and hit a key when you are asked to to boot from DVD. To fix the corrupted MBR, DBR or BCD, you just need your Windows installation DVD. How to Disable UEFI and Enable Legacy/CSM Boot Support. How to Set Windows 8 PC to Boot with Legacy BIOS Mode Instead of UEFI Mode. To learn more about how to change the boot mode, please check these articles: When you get the error message “Operating system not found or missing” during boot, try to change the boot mode from Legacy to UEFI, or turn off UEFI and Seure Boot, it might fix your problem. If you installed Windows 10/8 on a MBR disk, it also cannot boot in UEFI mode. If you configure a UEFI system to boot in Legacy mode, you’ll get the error message that saying operating system is missing or not found. The operating system installed on a GPT partition can only be booted in UEFI mode. Most Windows 10/8 computers come with UEFI firmware and Secure Boot enabled. Solution 1: Enable / Disable UEFI Secure Boot In this tutorial we’ll guide you how to troubleshoot the problem of operating system not found / missing in Windows 10 or 8. This issue can be caused by various reasons, such as MBR (Master Boot Record) or DBR (DOS Boot Record) is damaged, the BCD (Boot Configuration Database) is corrupt, or your system partition is not active. You can also use third party MBR recovery software or if you´ve created a MBR backup, restore it from there Partition Recovery has such capabilities).While booting Windows 10 or 8 computer, you might receive the following error message: When you are logged on, you can run the FIXMBR command to fix MBR. Choose the repair option during setup, and run the Recovery Console. If you have Windows NT / 2000 / XP, you can boot from startup floppy disks or CD-ROM. The simplest way to repair or re-create a MBR is to run Microsoft´s standard utility called FDISK with a parameter /MBR, as follows.įDISK is a standard utility included in MS-DOS, Windows 95, 98, ME. Check whether the disk signature (0x55AA) is present or not. Check whether error messages (as above - "Invalid partition table"…) are present or not. Check to see if it may have been filled up with zeros or any other single character. The first thing to do if the computer cannot boot is to runĪ Disk Viewer and check the first physical sector on HDD to see whether it looks like a valid MBR or not: When trying to boot now, an error message like "Operating System not found" will appear. MBR is damaged What will happen if the sector signature (last word 0x55AA) has been removed or damaged?