ShuffleList.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace StackOverflow
{
    class Program
    {
        static void Main(string[] args)
        {
            var list = new List<int>() { 1, 2, 3, 4, 5, 6 };
            PrintList(list);

            var rnd = new Random();
            var shuffled = list.OrderBy(x => rnd.Next()).ToList();

            Console.WriteLine();
            PrintList(shuffled);

            Console.ReadLine();
        }

        static void PrintList(List<int> list)
        {
            foreach (var item in list)
                Console.Write("{0} ", item);
        }
    }
}