string[] ad = new string[4];
            ad[0] = "mehmet";
            ad[1] = "ali";
            ad[2] = "veli";
            ad[3] = "burak";

            string[] yeniAd = ad.OrderBy(i => i).ToArray(); //a-z
            string[] yeniAd2 = ad.OrderByDescending(i => i).ToArray(); //z-a