Why not display incoming calls

Is your display on your phone working, and its just that the incoming calls notification is not working when you recieve calls? Have you tried a hard reset? (battery pull)
If your phones display is functioning, then more then likely it has to do with your settings of your phone. A long time ago with a older phone I had, I accidentally some how turned off my phones incoming calls notification. I was able to remedy this, but calling the phone company and they walked me through how to go into my phones settings and turn the incoming calls notifications back on. I would try this if you cant find it under your phones settings to turn the incoming calls notifications back on. Hope this helps. ;)