How To: Rescue Windows 7 Boot Manager / "Bootmgr is missing"

Overview

Constraints

Preparations

1. REQUIRED: Windows 7 rescue disk
1. To create:  navigate to Control Panel | System and Security | Back up your computer  and select Create a system repair disc and then follow the direction as appropriate for your situation.

Steps

Step 1: Boot from Windows 7 rescue disk and answer language and keyboard layout questions for your situation.

Step 2: Select your OS and check the Use recovery tools that can help fix problems starting Windows

Step 3: On the System Recovery Options window, select Command Prompt 

• Note: I recommend skipping down to Other Observations before you continue on Step 4.

Step 4: Enter each of these commands, waiting for each to finish before starting the next one:

bootrec /rebuildbcd
bootrec /fixmbr
bootrec /fixboot 

Step 5: Remove Windows 7 Rescue disk and reboot

Step 6: If it boots normally, you're done. If not: execute Steps 1-3 again and then continue on Step 7

• Note: I used the following steps without checking the results at Step 5 and Step 6.  While probably not recommended, it does appear to be OK.

Step 7: Execute these commands, waiting for each one to finish before starting the next one:

diskpart

Inside diskpart, type each following line:

select disk 0
list volume

Step 8: Locate your Windows 7 Rescue disk (IE CD/DVD) and note the drive letter and then type exit to exit diskpart.

Step 9: Execute these commands, waiting for each one to finish before starting the next one:

Change to what ever the drive letter was listed in diskpart for the Windows 7 Rescue disk listed in Step 7

Example: D:

Continue with these commands:

cd boot
dir
bootsect /nt60 SYS /mbr

Step 10: remove Windows 7 Rescue disk and reboot

Observations

This process is likely to remove any custom Boot Manager options you have previous setup.  See the Other Resources link to learn how to perform backups on you Windows 7 Boot Manager configuration before putting it at risk on Step 4

Summary

Assuming you have only unlinked your MBR from the boot process for Windows 7, these instructions should repair this minor, MBR-based mis-configuration.  If there is more extensive OS file damage or physical hard drive damage, these steps may not provide any assistance.

Resources

Here is where I got my information from:   

1. Fix the MBR – Guide for Windows XP, Vista, 7, 8, 8.1

Other Resources

Here are additional resources which might be useful, depending on your situation:

1.  How to Use the BCDEDIT Command Line Tool

Disclaimer

This solution worked for me. It may or may not work for you. I am not responsible for your actions nor the your results of your actions should you act on what you read here. I do not claim expertise in this very specific area and only convey my experience. There is no warranty on this (and most) free information.