If you are running Oracle APEX that comes with Oracle XE installation, chances are that you are still making use of Embedded PL/SQL gateway, which essentially uses Oracle XML DB HTTP component. In reality this means that all your files are stored in the database itself.
Simply dragging your files to the /images directory of apex will not have any effect as one would have hoped; frequent changes to your javascript files or images is quite common during development and therefore can be very annoying sometimes.