The codes are in the box in your closet. The keypad is just the "key" to the lock of the system, sort of speak. The box is the brains (or lock, if you will). You may not even need a new keypad to use it the way you speak of. As long as all the buttons work on the keypad, the screen is just info stuff. This will not bother the system usage. You will have to figure out which type of system you have and many people on here and many other sites on the net can tell you the way to "default" the system. This takes it back to the original factory codes. From there you can make the code what you want, with a little help (or a manual). You need to look in the box in your closet to find out what type of system you have. Do a yahoo search with the system type you have and find an installation manual. Or you can edit this question with the model info and we will help you further. Good luck...
Apartment Maintenance Supervisor