I have a Nikon D3100 with the 18-55mm lens, for some reason it own auto focus now?

I usually use it for fishing and never had a problem with it (doesn't get wet and I look after it) everything works on it and I've cleaned the connectors, taken the battery out and the card, put it all back in and still doesn't auto focus.

Added (1). The lens is on auto mode

Added (2). The motor won't work at all, I can use it in manual and that's it. Tried resetting to factory setting etc

Is the switch on the lens set to autofocus or manual focus?

Can you be more specific. Is it hunting for a focus point, or the motor just won't turn on?

Have you tried going to info and see if you set it of auto, Single servo, active or manual?

For fishing, use a fishing rod, a line and a hook or you could bring the boat to where the fish are and use a net. A camera is used for taking pictures.

Bring the camera and lens back to the store. Either they point you to their authorized service center or they bring your camera there themselves.