Go to file manager on your mobile,
In the "Settings" option,
Choose system folders,
In the "System" folder there's a file called "MMCSTORE",
Send that to your PC using IR/Bluetooth,
Then open it in notepad.
The password you need for your memory card is in that file
my advise is to try to remember your password, as it is a very complex and involved procedure AES decrypting files. I did some research regarding the password protection side of a transcend 4GB USB, found they have a Zip Function: Compress and/or password protect saved files using AES Encryption.
decrypting isn't an option. as this are designed to be secure.
so try remember that password :P