using System;

using System.Reflection;

public class Program

{

    public static void Main()

    {

        typeof(A).GetMethod("InternalMethod", BindingFlags.Static | BindingFlags.NonPublic).Invoke(null, null);                          

    }

    public class A

    {

        internal static void InternalMethod()

        {

            Console.WriteLine("U mnie działa!");

        }

    }

}