Camera works at night but goes blank during daylight hours

Just like the human eye your camera has an electronic iris that automatically opens and closes to adjust to varying light levels. It appears that the internal light compensation circuit is stuck open. That is why you have a picture at night but not during the day - there is simply too much light entering the camera during the daytime. Try disconnecting the power from the camera for a minute or so and then repower back up. After several attempts if this does not work then you will need to replace the camera. One thing you do not mention is the type of lens on the camera. You will either have a standard lens that simply brings into focus the image or one with a cord that plugs into the camera. This type has a built-in auto iris feature which also controls incoming light levels. If your camera uses the standard lens (no cord) you may be able to purchase an auto iris type lens to compensate for the camera's malfunctioning internal circuitry. If you need additional help please contact me.