A feature(button) phone keypad can stop working due to water damage or technical issues on the phone’s motherboard, if your phone’s keypad buttons stopped working after your phone contacted liquid or water, then you should try and remove the water by drying the phone with a piece of cloth, exposing the phone to sunlight or a fan.
If the solutions above didn’t solve the problem or if your phone did not had a contact with water before developing the non-responsive button problem, then you will need the service of an experienced phone repair engineer, you can click here to request for our phone repair service, because at Chrisrepair.com we offer swift and hassle free phone repair services.