Having trouble with a disk

DISKPART> list disk

Disk ### Status Size Free Dyn Gpt
——– ————- ——- ——- — —
Disk 0 Online 186 GB 0 B
Disk 1 Online 9 GB 0 B
Disk 2 Online 232 GB 0 B
Disk 3 Online 0 B 0 B

Disk 3 is connected via USB to a Windows 7 machine and was once a working HD with Windows XP on another machine. What does it mean 0 B for size? Also, it will not initialize in disk management. Please help! Thanks in advance.