Windows – Grub rescue, unknown file system. Can’t boot into Windows 7

bootloadergrubpartitioningUbuntuwindows

I am confused, so I am also going to use this question to get clarification and fix my computer.

Some background: I had Windows 7 on a 1 TB HDD and decided to partition my hard drive into two ~500 GB partitions, one for Windows 7 and one for Ubuntu or whatever flavour I desired (like a sandbox partition…)

I installed Ubuntu but the installation had issues so I decided to uninstall. Note before the uninstallation I had to press f12 when I turned on to boot from my primary HDD, then choose what OS I wanted to use. Undesirable, but it worked.

Anyway, after I decided to uninstall Ubuntu I went into Windows 7 > Start > Computer > Manage and deleted the EXT4 filesystem (Ubuntu partition) giving me 4xx GB of free space. However when I restarted Windows 7, I am now unable to boot Windows.

When I DON'T hit F12, I see a blank screen with a flashing underscore.
When I DO hit F12, I choose my primary HDD, and then I get a GRUB error:

Unknown filesystem:

grub rescue> _

Something I'm unclear of: GRUB boots linux partitions, right? What boots Windows? Is GRUB "overwriting" the Windows bootloader? How can I completely get Windows back to normal? (IE, It boots automatically without hitting F12.)

Thanks for any help, I'm on a live CD version of Ubuntu right now until I can get back on Windows.

Best Answer

GRUB works in stages. First part of it is loaded from MBR (Master Boot Record), which points to secondary data located on your Linux partition that is required to proceed with next step of grub. From your description of the problem, apparently you have deleted the second stage of your grub installation and grub isn't able to find it.

In order to get back your Windows 7 boot loader on your MBR, to allow you to boot into Windows 7, follow these steps:

1- Boot your computer from your Windows 7 install dvd.

2- Choose your language, time, and keyboard input on the first screen, and click next.

3- On next screen, you will be presented with three choices. Click on "Repair Your Computer", to enter recovery window. Now select "Command Prompt". At the command prompt, first change your directory to boot (cd boot), and then type "bootsect /nt60 C:\". This will restore your windows boot loader onto your MBR.

Now restart your computer, and you should be able to boot into your Windows 7 installation.

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