My panasonic cordless phone model

Try resetting the system. Unplug base from power, unplug all phone lines, remove all batteries from handsets. Wait two minutes. Put handsets on their cradles. Reconnect phone and power to restart the system. If that does not work then the phone is faulty. You can try disconnecting handsets, but probably it is the main unit. In that case call Panasonic at the number on manual , or replace the phone.