Nikon D3100 is displaying all my images as black, why

Ever since I've got it I've expperienced problems!
As of a month ago, every time I take a picture with it, the images appears bllack. As if I took a picture of a black wall!

Yes the lens cap was off and yes it had enough charge

A normal lens, normal battery and all…

Maybe check the aperture and make sure its open wide enough and maybe slow down your shutter speed.

Check your setting to make sure you are not under exposing the photo. Also did you try uploading the photo to your computer to check whether they are normal or all are back? Maybe the LCD is faulty and not functioning.

You are giving no information as to how you are using the camera. In P mode? In full Auto? In any of the semi auto modes? In M manual mode?

Do this. Look in your owners manual to see how to reset the camera to all it's factory default settings. Then put the camera in AUTO. Try taking some photos in good light. If you still can't see photos on the camera monitor in review mode, do as the other person said and try downloading them to your computer. If you still have no photos, there's something wrong with the camera. If you do have the photos on the computer, then you know that the camera monitor is at fault.

Sounds like operator error but to confirm do this test
Set the camera to full auto (green auti symbol on your mode dial)
Take a photo out in the street in bright daylight

Is it OK?
If yes - operator error - underexposure - you need to learn about exposures
If no - the camera is faulty

Seriously now, did you actually take time to READ & STUDY the Owner's Manual for your camera or did you just figure out how to turn it on and then start playing with it, changing settings that you had no idea of what they did?

Watch this video tutorial: http://www.nikondigitutor.com/eng/d3100/index.html If Nikon can't teach you to properly use your Nikon D3100 then it can't be done.

Pictures that come out black are grossly underexposed.

99% of the problems associated with digital cameras are caused by the person using the camera.

READ & STUDY the Owner's Manual.

WATCH the video tutorial.

LEARN to use your camera.