if u can open up the panel.. go ahead..
take out u r battery..
open the top panel..
thers is a white sticker which sticks the keypad tensions(buttons) in order..
carefully peel off till u get u r required button(*, 5 & C )..
rub the copper plated circles under the key tensions with an INK eraser..
now u r done..
reassemble in order..

thats it u r done...

if not....change u r internal keypad..

post u r thanks..
gud luckssss..