My nikon d3100 has trouble focusing?

I've had my camera for almost 11 months now and its still in great condition. I have no lenes for it but i'm in the process of saving up a light for the camera (what jc caylen uses for his youtube videos), do you know what light you'd get for my type of camera? Anyways. A couple days ago i wanted to film for youtube channel so i got my camera ready, one problem - it won't focus on me unless i'm really close to the camera - it's super annoying because when i move a little further away (say 10cm away because i sit on my bed whilst filming) it always goes out of focus. I have fairy lights in the background and a canvas of a beach but they shouldn't be the problem. How can i get my camera to focus on me when i'm not super close to the camera. ALSO please break down things for me because i'm not smart and i'm not good with farrenheight's or AFM's etc.

Am I reading this correctly?

You have a Nikon D3100, but NO Lens, not even the 18-55 mm that came with it?

If not, you are missing the device used to focus light on the cameras sensor… A lens.

If you are using the lens that came with your camera, then you need to make sure that the camera and lens are set to the auto-focus modes.

Most videographers actually use manual focus and a LCD loupe to assure sharp focus of their subject.

Try that and see what happens… That is if you do have a lens. If you don't have a lens, they you need to buy one

Simply put, without a lens, your camera is useless. Buy a lens first, lights later.

Okay, so you obviously have a lens, without you knowing it. The fact that you see yourself when up close means something is attached to that huge gaping hole in front of your camera. I assume you are shooting alone. Place the camera on a tripod or a stack of books on the table. Set it to fire using the self-timer. Set up a chair where you will be sitting or standing for the picture. Focus on the chair. Lock focus by switching AF off. Press the shutter release button then run into position. Pose, hold your breathe and smile and wait for the camera to fire. If you come up blurry, use flash.

First, the camera and lens have to be in Auto not Manual. Look on the side of the lens to make sure it is in A for autofocus.