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

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)

 

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:

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