Ok. Neither clicking on the button on the screen nor pressing the return key works....
You probably have OS 4.6 or newer, correct? If so, see if you can boot in safe mode. If you don't know how, see KB17877-How to start a BlackBerry smartphone in safe mode
If you are able to boot in safe mode, see if you can unlock the device.
EDIT: Where I'm going with this, is the assumption that if it is some software corruption, you may be able to unlock it in safe mode. And if so that is an indication that it is a software glitch. The question then will be what third-party apps you may have installed, or third-party themes. While in safe mode you will want to do a full backup and then uninstall those third-party items that are suspect, and then try booting up in regular mode and unlocking. If that fails, you can try deleting some other stuff and try again, or just decide at that point to wipe with JL_CMDER and then reinstall the OS. But if you can backup in safe mode, by all means do a full backup first thing.