If your machine is stopping very early in the boot up sequence and telling you that BOOTMGR is missing, that means your Windows 7 or Windows Vista machine cannot find a bootable drive to start from, or the software on your bootable drive is damaged. (for Windows XP go here)
The first step is to make sure you are booting from the drive you expect. Unplug any USB drives or peripherals and eject any CDs and floppies. Shut off the machine and try again. If you’re lucky, it will boot OK. If not, carry on…
Second step, turn the machine off and open it up if it is accessible. Unplug and replug all of the drive cables and PCI/PCI-e cards, put it back together, and try starting. Still happening? Following are several methods to fix, starting with the easiest and getting more technical.
General troubleshooting hint: Always use a cabled keyboard and mouse for doing troubleshooting. Wireless devices don’t work until drivers are loaded — and the input you need to give the machine has to be done way before Windows loads the drivers. Similarly, if your machine is not responding to USB keyboard input, and it has round PS2 (green and purple) mouse and keyboard ports, find a PS2 keyboard and plug that in for doing troubleshooting.
Startup Repair
Do a Startup Repair of Windows, this will replace any damaged Windows files on your drive without altering your data or programs (although it is prudent to have your data backed up if possible before doing any repairs). To do the Startup Repair you need to boot from a full Windows 7 or Vista DVD.
Note- if all you have are the Restore disks from the computer’s manufacturer, you may not be able to do a Startup Repair depending how the disks are configured. You do NOT want to do a Restore or Factory Reset
- Remove any USB flash drives or external hard drives
- Put the Windows DVD in, restart the machine,
- Watch the screen for the prompt “Press any key to boot from CD or DVD” and
- Press a key to boot from the Windows DVD.
- After it has booted, respond to the Language choice, region and keyboard choices, and hit Next.
- On the next screen, choose Repair Your Computer – do not choose Install Now.
- The System Recovery Options screen will come up, and it will search for Windows installations to repair
- Unless you have multiple systems, it should come up with one Windows installation, choose that and click Next
- Click on the Startup Repair option, follow the prompts and accept the changes suggested by the installer.
- The installer may (or may not) reboot the machine during the process. Leave it alone to do so, do NOT hit a key and make it reboot from the Windows DVD.
- When it is finished, you will get a dialog box, click the Restart your computer to complete the repairs button
If Startup Repair did not fix the problem, then you will have to take additional steps.
Writing a new Partition Boot Sector
This will replace corrupted boot information with good files, allowing the partition to be bootable.
- At boot time, press F8 to go into the Advanced Boot Options menu
- A menu will come up, choose Repair Your Computer
- Note: if you are using Vista and you don’t have a Repair Your Computer option, that means that System Recovery Options was never installed with Windows on your machine. You will have to boot the machine from a Windows Vista DVD to access the option. Different ways to get to System Recovery Options
- In the System Recovery Options menu, choose Command Prompt This will bring up a text screen with a cursor
- Type in (make sure to include the space)
bootrec /fixboot
and then press the Enter key - After it has written the boot sector files, you should see a message The operation completed successfully. Restart your machine now, and it should boot up.
Boot Configuration Data
If this didn’t work, you can try rebuilding the Boot Configuration Data Instructions are in this link.
BIOS Setup
You can also check in your BIOS Setup to make sure that the boot order settings are correct.
Hardware:
Finally, keep in mind that a software error may be a result of a hardware failure. What looks like a Windows issue may be a dead or dying hard drive, bad data cables, a motherboard failure or failing RAM. Testing the hardware should be part of your diagnostic efforts. Intermittent hardware failures are the troubleshooter’s nightmare, if they appear at random or only in certain circumstances. Heat is the culprit sometimes, make sure that the fans and cooling systems of the machine are functional, and that the vents are clean and free from obstructions.
Sometimes, a Windows problem is un-solveable and can consume an inordinate amount of time. At that point, cutting your losses and installing a new hard drive with a fresh install of Windows may be the lowest cost solution.
Resources:
Windows 7 Startup Repair: http://pcsupport.about.com/od/toolsofthetrade/ss/windows-7-startup-repair.htm
Windows Vista Startup Repair: http://pcsupport.about.com/od/toolsofthetrade/ss/windows-vista-startup-repair.htm