Help,don't know why script not working!

I put in this script and a bunch of errors came up, what did I do wrong!!!

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour
{
public float gravity = 1f;
public float gchange = 0f;

void Update()
{
	if(gchange < gravity);
	{
		gameObject.rigidbody.useGravity(false);
	}
}

}

Hiya. What you need here is useGravity = false; instead of useGravity(false).

You had a semicolon in the if statement, and useGravity is a static variable (it needs to have = not ())

void Update()
{
    if(gchange < gravity)
    {
       gameObject.rigidbody.useGravity=false;
    }
}