Fix MBR or Operating System Not Found in Windows 7

Back when I first started playing with different Linux distributions, like Ubuntu, I’d accidentally wipe out the boot loader. I had been through this scenario in Windows XP countless times and I knew how to restore the Windows master boot record.

win7-logoThis time, it happened to me in Windows 7. I was playing around with a Linux boot loader utility and I accidentally trashed the MBR (master boot record). I ended up with a really weird message when I went to restart the machine. It wasn’t Operating System Not Foundbut I knew what had happened.

Fortunately, I had created a Windows 7 Repair disk. If you haven’t done this yourself, take a few minutes and do it now.

Create a Windows 7 Repair Disk

  1. Insert a blank CD
  2. Click on the Start button and type repairinto the search box.
  3. Click on Create a System Repair Discand follow the instructions.


Repairing a missing or corrupted boot record

Let’s assume that you have either a Windows 7 Installation DVD or a repair disk. Here’s the scoop on how to fix a missing boot record, or some other weird boot error.

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Clif Sipe

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  • Emmanuel – opensourceguy

    Thanks man! Your steps were straight forward. The /fixmbr command did it for me, after encountering a grub rescue message (i had deleted a partition containing ubuntu).

  • Bijan

    My system only shows “operating system not found” and can not go further!
    Unfortunately, I didn’t build the Recovery DVDs before, so I borrowed my friend’s Recovery DVD to become able to start the system and go to recovery section.
    for your information, my laptop is “SONY VAIO VPC-F12FFX/B” and his model is “VPC-F111FX” that are very similar (but of course, their DVD can not use completely for another)

    The problem is that your step-by-step solutions seems to be OK (and its almost the same as Microsoft Solution Center and some other sites); but in this Algorithm, no one stated the point that our result is different than something that should appear there!


    Let’s return to my problem:
    In Step 6 , I should be able to see my missing operating system and of course, I should select it. But why nobody didn’t tell that if nothing shows, what should be our next step?

    Anyway, after doing some “try & error” ways, finally I become able to go to your 7 section titled “Select a recovery tool”
    As explained above, I couldn’t try “System Restore” (because Recovery DVD’s was not mine), and instead, I selected “Start up Repair” and followed its orders, but after restarting my computer, nothing solved :(

    I did it once again and then, I went into Command Prompt and tried “bootrec.exe” first with /fixmbr and then, with all of 3 other parameters (of course, I restarted my system after any changes)

    The only result is that my system error changed to:
    “BOOTMGR is missing”

    I know that there are special methods for solving this problem, but a very strange thing is that when I want to try the “System Restore” in “Select a recovery tool” section, windows will do some show-off and then says:
    “Startup Repair cannot repair this computer automatically”
    and wants me to “Send information to Microsoft”!

    for your information, problem details, as it says, are:
    Problem Event Name: StartupRepairOffline
    Problem Signature 01: 6.1.7600.16385
    Problem Signature 02: 6.1.7600.16385
    Problem Signature 03: Unknown
    Problem Signature 04: -1
    Problem Signature 05: ExternalMedia
    Problem Signature 06: 1
    Problem Signature 07: MissingBootManager
    OS Version: 6.1.7600.
    Locale ID: 1033

    My question is that, If we should try again the triple magic
    “bootrec /RebuildBcd” ,
    “bootrec /FixMbr” and
    “bootrec /FixBoot”,
    why the Microsoft “Startup Repair” program was not able to knew that?

    Oh! I tried of typing, I don’t know what happened to your mind :)

  • Josh Wood

    At step 6 it doesn’t find my windows 7 installation

  • angelobeltran

    What happens then if you have no os listed under STEP 6?