C# How can i change the PNG texture in gameObject in runtime

Unity Engine
1 
if (GUI.Button(new Rect(20,435,140,70), "PNG texture",guiStyle))
        {
			//Texture2D texture = Resources.Load("Crate.tga") as Texture2D;
            //GameObject.Find("Sphere").transform.renderer.materials.mainTexture[1]=texture;
			//Object[] textures = Resources.LoadAll("Textures", typeof(Texture2D));	
			 //WWW www = new WWW("http://l.yimg.com/rz/d/yahoo_frontpage_zh-Hant-HK_s_f_p_97.5x56_frontpage.png");
        	//yield return www;
			//GameObject.Find("Sphere").transform.renderer.materials[1].mainTexture= www.texture;
				//var filePath = Application.dataPath + "/Resources/tux.png";
				//guiText.text = filePath;
				//if (System.IO.File.Exists(filePath))
				//{
				   // guiText.text += " EXISTS!!!";
				   // var bytes = System.IO.File.ReadAllBytes(filePath);
				   // var tex = new Texture2D(1, 1);
				  //  tex.LoadImage(bytes);
				  //GameObject.Find("Sphere").transform.renderer.materials[0].mainTexture = tex;
				//}	
				Object[] textures = Resources.LoadAll("Textures", typeof(Texture2D));
				Texture2D texture = Resources.Load("UserInterface/Skins") as Texture2D;
				GameObject.Find("Sphere").transform.renderer.materials[0].mainTexture = texture;

        }

I have find a lot of method that about how to change the texture(PNG image) into the gameobject, however, i cannot make it work.Anyone can help mt to solve the problem?

btw, i can change the color of my gameObject during runtime.

Thanks!

2

All your textures and materials in a file called Resources?

3

Yes, the Skins.png is under Resourse/UserInterface

however, i cannot change the PNG texture after pressing the button, it only work in change the color, during run it in my android Device