It's okay that it doesn't work.
Hashing is a one-way procedure. No Hash can be 'decoded' to the original value.
What you are doing in your unHash method is hashing the hash again!
If you want to scramble passwords and unscramble them at a later time you need to look for Encryption/Decryption.
It can also be done with the Java Cryptography API.
Try this: http://www.devx.com/Java/10MinuteSolution/21385/1763/page/2