ScoreManager.cs

using UnityEngine;
using UnityEngine.UI;
using System.Collections;

public class ScoreManager : MonoBehaviour {
	public static int score;

	Text text;

	// Use this for initialization
	void Start () {
		text = GetComponent<Text>();

		score = 0;
 	}
	
	// Update is called once per frame
	void Update () {
		if (score < 0)
			score = 0; 
		text.text = " " + score;
	}

	public static void AddPoints (int pointsToAdd) {
		score += pointsToAdd;
}

	public static void Reset () {
		score=0;
	}

}