Quaternion.identity
static var identity: Quaternion;
static Quaternion identity;
static identity as Quaternion
Description

The identity rotation (Read Only). This quaternion corresponds to "no rotation": the object.

Is perfectly aligned with the world or parent axes.
	transform.rotation = Quaternion.identity;

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Example() {
        transform.rotation = Quaternion.identity;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Example() as void:
		transform.rotation = Quaternion.identity