Hard-drive unallocated

Before I get into the direct details, some backstory to help you guys understand:

I had a 1tb external hard drive. I was stupid and tripped over the usb cable, essentially breaking off the usb port on the external. I opened the external up and the actual HD was fine, unaffected, but the attached chip that house the power port and usb hub was... well, it was fine, except the usb port was ripped off. That's the backstory.

I have 4 HD compartments in my computer, and 2 were currently being used, leaving me 2 free ones. I connected the HD from my external as well as another old hard drive I had sitting in a drawer for a while (I mean, what the heck). Well, my computer only recognizes the old hard drive, not the external HD I shelved in my comp.

I went into disk management, and in disk 2 I can see my HD, but it's unallocated. Thing is, I can't just format it — I have crucial information on there. I'm not sure where to go from here. Only alternative I can think of is buying an HD enclosure, but I don't think that would make a difference, and on top of that, if it doesn't, I just wasted a bunch of money.

Here's a screenshot of the disk:

http://img844.imageshack.us/img844/3010/asasac.png

Disk 2 is the one I need.