Why won't my nikon d3100 take pictures on auto mode?

I've tried to change the settings and for some reason it will only take pictures on manual mode. Some people have told me it's locked on manual but I don't really know what that means or how to fix it. Can anyone help? I'm new to this camera, I've got it yesterday.

If the camera can't focus, it won't shoot.

Switch the control on the lens to AF and READ YOUR MANUAL! It's the best friend you'll ever have.

See if the dial on the top right is set to auto. Check the lens for this setting as well. If all else fails, read the owners manual.

Http://keerok-photography.blogspot.com/2011/12/common-reasons-why-camera-wont-shoot.html

On the side of the lens is an AF switch, turn it to off, set the mode dial to AUTO and see what happens. Also try it on P, A and S. You can't "lock" it on manual other than having the mode dial rotated and set on M.

Make sure the battery is fully charged. You can check that by pressing the shutter button half way down or turn the camera off and then on. The display will come on and look for a little battery ikon and see how many bars are lit. If the battery is very low, the flash will not operate and if the camera is set to auto, it will try to fire the flash if it's too dark. You can also try taking the camera outside or holding it near a window to see if the shutter will operate. You can also turn the mode dial to the little lightning bolt setting one notch below the auto setting. In this mode, the camera will operate in the auto mode, but it will not fire the flash no matter how dark it is, but it will click the shutter.

Study the operator's manual that came with the camera, but the hard copy is abbreviated. The complete manual is on the CD that was included with your camera.