I had my 1 TB WD hard disk plugged into my laptop and when the laptop hung, I had to force restart the computer. On re-started it showed me this dreaded message-
The disk you inserted was not readable by this computer
The drive is probably corrupt. You might try a Linux Live CD and boot from that and see if you can access your data. Then there is recovery software Recuva http://www.piriform.com/recuva/download is free and might work. There are also several try and buy programs too.