why white screen color appear on face of phone and disappears(visa vis)

A

AC Question

For some time my motorola phone is behaving in wired a manner.
if it is on a white screen appears on the face on the phone and latter disappears again and reappears again until you use it for long when it is on the white face will disappear but when it goes off the white face will come on top of the face.what can i do to restore it back to normal.