Yes, tried almost everything.Have you tried a reset?
Well yes, there is a lever which opens live view. I looked on youtube how ppl record on this camera, tried same things. Also, there is no video mode. Looks like its just a record button i posted a video asking for help on other sites but no luck. Here's the video that i took.Shot in the dark since I cannot see your camera settings. Is there a lever or slide switch by the Live View control for changing to video? Perhaps set the mode dial to Auto. Unless that is where you change to video mode. I do know that generation requires you to change from photo to video mode.
camera is in Auto Focus mode, tried all of the focus modes. Nothing. I guess there is a problem with the lens, or the camera.D3100 user manual can be downloaded here: https://downloadcenter.nikonimglib.com/en/products/19/D3100.html
Pages 45-46:
So basically, at least try to press the shutter-release button to acquire a focus before pressing the record button. The person in your video never tried that.
- Rotate the Live View switch on
- Choose a focus mode with the "i" button at the lower left corner of the back
- Choose and AF Area mode as described on page 38
- Focus (perhaps you are on manual focus and not adjusted?)
- Record by pressing the movie record button in the center of the Live View switch