The locking system of the application is designed in a way that only lets the user who knows the password access the files. Once you lock the files, they are stored and encrypted on the device. Most likely, you used a different password, and because of that the files are locked. There is no possible way of removing the encryption if you don't know the password. Try to remember it and then log-in in the application.
For additional help, I recommend contacting the developer through the Help > About section in the application.