The memory card is full. Transfer pictures to your computer or change the memory card. Camera does not turn on. Batteries are not installed properly. Remove the batteries and install them according to the directions on the inside of the battery door.
Batteries are weak or depleted.
Install new batteries or use the AC adapter. Part of the picture is missing. Something was blocking the lens when the picture was taken. Keep hands, fingers, or other objects away from the lens when taking pictures. Your eye or the picture was not centered correctly in the viewfinder.