var textures : Texture2D[];
var delay = 1.0;
private var textureCounter = 0;

function Start () {
    InvokeRepeating("CycleTextures", delay, delay);
}

function CycleTextures () {
    textureCounter = ++textureCounter % textures.length;
    renderer.material.mainTexture = textures[textureCounter];
}

i have attached this script to the gameobject which i wish to change texture but nothing is happening. any ideas why?

This Script works parfectly.