How to Fix Windows Boot Manager Without a Disk: 10 Effective Solutions

If you encounter the dreaded “BOOTMGR is missing” error when trying to boot your Windows computer, don’t panic. There are several effective ways to fix the Windows boot manager without needing an installation disk. In this comprehensive guide, we’ll walk you through 10 proven solutions to get your system back up and running.

1. Unplug External Devices

One of the simplest fixes for a missing BOOTMGR is to disconnect any external storage devices connected to your computer. This includes USB flash drives, external hard drives, and even floppy disks. If these devices are not bootable, they can cause the BOOTMGR error to appear. Once you’ve unplugged the external devices, try restarting your computer to see if the issue is resolved.

2. Check Boot Order in BIOS

If your system hard drive is not set as the first boot device in your computer’s BIOS, your machine may attempt to boot from another drive that doesn’t have the necessary boot files. To fix this, enter your BIOS settings (usually by pressing a key like F2, F12, or Del during startup) and ensure that your system hard drive is listed first in the boot order.

3. Repair Master Boot Record (MBR)

A corrupted Master Boot Record (MBR) can also lead to a missing BOOTMGR error. You can repair the MBR using the bootrec command in the Windows Recovery Environment. Here’s how:

1. Boot your computer from a Windows installation USB drive or DVD.
2. When the installation screen appears, click “Repair your computer”.
3. Select “Troubleshoot” > “Advanced options” > “Command Prompt”.
4. In the Command Prompt, type the following commands and press Enter after each one:

   bootrec /fixmbr bootrec /fixboot bootrec /rebuildbcd

5. Exit the Command Prompt and restart your computer.

If you don’t have a Windows installation media, you can use a third-party tool like MiniTool Partition Wizard to create a bootable USB drive or CD/DVD. Then boot from the device and use the “Rebuild MBR” feature to fix the issue.

4. Rebuild Boot Configuration Data (BCD)

Another solution is to rebuild the Boot Configuration Data (BCD) using the bootrec command. Here’s how:

1. Boot from a Windows installation media and select “Repair your computer”.
2. Go to “Troubleshoot” > “Advanced options” > “Command Prompt”.
3. In the Command Prompt, type the following command and press Enter:

   bootrec /rebuildbcd

4. Follow the on-screen instructions to rebuild the BCD.
5. Exit the Command Prompt and restart your computer.

5. Perform a System Restore

If you have previously created a system restore point, you can use it to undo recent changes that may have caused the BOOTMGR error. Here’s how:

1. Boot from a Windows installation media and select “Repair your computer”.
2. Go to “Troubleshoot” > “Advanced options” > “System Restore”.
3. Select a restore point and follow the on-screen instructions to complete the process.
4. Restart your computer and check if the issue is resolved.

6. Run System File Checker (SFC)

The System File Checker (SFC) is a built-in Windows tool that can scan and repair corrupted system files. To run SFC:

1. Boot from a Windows installation media and select “Repair your computer”.
2. Go to “Troubleshoot” > “Advanced options” > “Command Prompt”.
3. In the Command Prompt, type the following command and press Enter:

   sfc /scannow

4. Wait for the scan to complete and follow any on-screen instructions.
5. Restart your computer and check if the issue is resolved.

7. Use Windows Startup Repair

Windows Startup Repair is a built-in troubleshooting tool that can automatically diagnose and fix common startup issues. To use it:

1. Boot from a Windows installation media and select “Repair your computer”.
2. Go to “Troubleshoot” > “Advanced options” > “Startup Repair”.
3. Follow the on-screen instructions to complete the repair process.
4. Restart your computer and check if the issue is resolved.

8. Perform a Clean Boot

A clean boot starts Windows with a minimal set of drivers and startup programs, which can help identify if a third-party application or service is causing the BOOTMGR error. To perform a clean boot:

1. Boot into Safe Mode by pressing F8 during startup.
2. Press Windows key R to open the Run dialog.
3. Type “msconfig” and press Enter to open the System Configuration utility.
4. Go to the “Services” tab and check the “Hide all Microsoft services” box.
5. Click “Disable all” and then go to the “Startup” tab.
6. Click “Open Task Manager” and disable all startup items.
7. Close Task Manager and click “OK” in the System Configuration utility.
8. Restart your computer and check if the issue is resolved.

9. Scan for Malware

Malware can sometimes interfere with the boot process and cause a missing BOOTMGR error. To scan for malware:

1. Boot into Safe Mode.
2. Run a full system scan with Windows Defender or a third-party antivirus program.
3. Remove any detected malware and restart your computer.

10. Test Your Hard Drive

A faulty hard drive can also lead to a missing BOOTMGR error. You can use a tool like MiniTool Partition Wizard to perform a surface test on your hard drive and check for bad sectors. If bad sectors are found, you can use the chkdsk tool to shield them. If there are many bad sectors, it’s recommended to back up your important data and replace the hard drive.