Partition Magic changed my hard drive and now windows won't start

Today I installed Partition Magic on my Windows 7 pc because i wanted to format an ipod and windows couldn't do it. I now know that the program doesn't work with windows 7. When i ran Partition Magic, a message appeared telling me that some big number was not the same as something else and asked if i wanted to change it. Foolishly i clicked yes without looking into what this meant or what it would do. Now when i start my computer i get the Windows Error Recovery screen. When i choose start windows normally i get a BSOD with this error code:

0x0000007B (0xFFFFF880009A97E8,0xFFFFFFFFC0000034,0x0000000000000000,0x0000000000000000)

 

Can somebody please tell me what the program changed and what i can do to change it back. I can't even start my computer in safe mode or do a system restore. Please help.