The appearance ofblack spots on display can be caused by internal damage of the screen, pressure on the LCD or OLED screen, or dead pixels forming on the screen. On other occasions these spots may be visible upon dropping or applying excessive pressure to the phone. Elsewhere, the presence of moisture in the display layers may also form dark spots. Regrettably, these spots do not tend to fade away. The best alternative is to get the display screen repaired by a technician who would suggest that the screen be replaced.