Major Problem with File Vault 2 and Ext HD

[Martell]

I have a macbook (2.0Ghz intel core 8GB 1067DDR3 ram lat 2008 model) running OS X 10.7.3. and I used FileValt 2 to encrypt a 500 Gb My passport western digital hard drive. The hard drive has been working great but the last time I used it the hard drive cable became unplugged (meaning I didn't eject it properly) now when i reconnect the hard drive to my computer it asked me for my password like it normally does but when i enter my password it says it's incorrect. I know 1000% thats it's the right password! to confirm it i click the Show hint button to make sure. I've been using this HD daily for 3 months i know its right i have 2 HD's with the same password and the other one works fine. Is there anything to can do to repair/defrag or restore permissions? when i try to use disk utility it fix it i get the prompt to enter my password but it will not accept it! how can i repair the drive so that i will be able to enter my password and recover my data? please help