Password protected folder

Then you created an encrypted disk image.

If you can't remember the password, the data is unrecoverable.

Your only hope would be if you have a backup of that data that was made before you encrypted it.

You would need to clarify somewhat how you created this password protected folder to begin with, but chances are, you don't.

That's the entire point of encrypting something and locking it with a password, so that no one can access the data without the proper password.