Bootcamp Windows Partition Won't Boot After Accidentally Changing Boot-up Partition

[JordanSimps]

I was messing around with the startup partition on my Windows 7 partition on my Mac and accidentally changed it to the Mac OS X partition. So when I boot the Windows 7 partition it says the error message "Missing Operating System". This error also shows up when I try to boot the Windows 7 DVD from the Mac drive selector screen. My question is how do change the boot partition on my Windows 7 partition if the partition won't even boot? I really don't want to install a new Windows 7 partition.

Mac Specifications:
Type: Mac Pro (Mid 2012)
Processor: 3.33 GHz 6-Core Intel Xeon
Memory: 32 GB 1333 MHz DDR3 ECC
Graphics: ATI Radeon HD 5770 1024 MB
Software: OS X 10.8.4 (12E55)

 

[wrldwzrd89]

You have the Windows 7 boot disc, right? Boot from that. Instead of installing, though, choose to repair a broken Windows installation.

EDIT: How exactly did you change things? You might want to undo whatever you just did using the same tool.

 

[JordanSimps]

You have the Windows 7 boot disc, right? Boot from that. Instead of installing, though, choose to repair a broken Windows installation.

EDIT: How exactly did you change things? You might want to undo whatever you just did using the same tool.

When I boot from the Windows 7 boot disc it says the same message "Missing Operating System". I boot the Windows 7 boot disc from the OS X partition manager.

I changed the startup partition from Command Prompt while booted in Windows 7, so undoing what I did with the same tool is out of the question. I followed this tutorial to change the Windows 7 startup partition:

A. Open command prompt from Windows recovery option menu. Type diskpart at the command prompt.

B. At the DiskPart prompt, type in list disk. You will see the list of disk currently attached to your computer.

C. Now type in select disk n, where n is the disk number. In this example, disk 0 is selected.

D. Now that correct disk is selected, type in list partition to get a list of all the partitions on that disk.

E. To select the partition you want to set as active, type in select partition n, where n is the partition number.

F. Now that you have selected the disk and partition, mark it as active by just typing the word active and pressing Enter. Now the partition is set active.

G. Exit from the command prompt and run startup repair. Refer: Startup Repair: frequently asked questions

Tutorial Link: http://answers.microsoft.com/en-us/...artition/907c92bc-67ff-469c-8cd9-73e86f647de0