Why isn't my player moving?

Question

Why is my code not working?

using UnityEngine;
using System.Collections;

public class NewBehaviourScript1 : MonoBehaviour 
{
    public float moveSpeed;
    public Vector3 input;
    public Rigidbody rb;

    void Start () 
    {
        rb = GetComponent<Rigidbody>();
    }

    void FixedUpdate () 
    {
        moveSpeed = 2;
        input = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
        rb.AddForce(input * moveSpeed);
    }
}

Answer 1

After testing your code, the only conclusion I can come to is that you are not actually including a Rigidbody on your player. When we use GetComponent<t>(), we are referencing an existing component on the host GameObject.

Given your above code, on an object that contains a Rigidbody, the object moves quite clearly. I have included a recording, for reference.

---

Ensure your GameObject has a Rigidbody through code

You can add a simple tag to any script to force it to require a component. If said script is attached to a GameObject via the Inspector, the required component is added, too. You can do this with any Component; this is what it would look like if you forced your script to attach a Rigidbody:

[RequireComponent(typeof(Rigidbody))]
public class NewBehaviourScript1
{
    // ...
}