How to repair cell phone keyboard fault

Keyboard fault

my samsung x450 set keyboard does not work. how can i repair it. it seen normal but it is a faulted.

Answer

you change the the "U200" , "U201" , " U100" , "C207" , "U101" , "U300" , "U500" , "U600" and "CN301" ,"U400" it solve your problem for all time.ok