Disk showing approx. 50% less capacity

Hello all, and thank you for your help.
Im having quite a problem, i've had a 60gb disk in a server, thats 8gb for win and 60gb for storage. Yesterday we had a power loss or something, and when i turned on pc, it smelled like burned. I checked, and noticed a blown capacitor on motherboard, so I took 60gb disk and plugged it into other pc, where I originaly took it from. I noticed when I open My Computer, I could not access D: disk -it said there is a I/O problem and windows could not access it(I had it partitioned into 20gb and 40gb), so I thot, maybe its an error from the other pc. I formated it, and now when I check the disk space, it says 31gb, I already tried with Disk management, but I had no luck. Right now im downloading Knoppix and see what does it say.
So...Im asking you guys, what should I do, any answer would be greatly apreciated.