My Nikon D3100 won't auto focus anymore. Is it the camera body the problem or the lens?

I changed back and fort to auto focus and manual focus. I still can focus manually but I won't auto focus anymore, no matter what I do. But I'm about to send the camera to the manufacturer to apply the warranty but I don't know if I need to send the whole camera or just the lens.

Added (1). Just called Nikon, they won't do any troubleshooting just told me to send the lens because it has the motor, not the body. But still have some doubts because when I try to autofocus it won't make the tipical sound (chh chhh ) that I used to hear from the shutter button. They say that if I send the body and if this has nothing wrong they will charge me for the cleaning and maintenance of it.

Added (2). Just called Nikon, they won't do any troubleshooting just told me to send the lens because it has the motor, not the body. But still have some doubts because when I try to autofocus it won't make the tipical sound (chh chhh ) that I used to hear from the shutter button. They say that if I send the body and if this has nothing wrong they will charge me for the cleaning and maintenance of it.

Added (3). Just called Nikon, they won't do any troubleshooting just told me to send the lens because it has the motor, not the body. But still have some doubts because when I try to autofocus it won't make the tipical sound (chh chhh ) that I used to hear from the shutter button. They say that if I send the body and if this has nothing wrong they will charge me for the cleaning and maintenance of it.

Have you tried another lens? If not, you'll need to send both.

The auto-focus mechanism is in the lens.

It could be that the motor in the lens has failed, but that is rare.

Call Nikon and have them help you troubleshoot the problem before you replace your lens.

You will have to call Nikon for a RMA number in any case and they will tell you what you need to send to them.