[DllImport("user32.dll")]
public static extern int ExitFunc(int operationFlag, int operationReason);

Vypnúť windows

ExitFunc(1, 0);

Reštartovať windows

ExitFunc(2, 0);

Odhlásiť windows

ExitFunc(0, 0);

Kód v c#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace ShutDown
{
    public partial class Form1 : Form
    {
        [DllImport("user32.dll")]
        public static extern int ExitFunc(int operationFlag, int operationReason);

        public Form1()
        {
            InitializeComponent();
        }       
        protected void btnRestart_Click(object sender, EventArgs e)
        {
            ExitFunc(2, 0);
        }
        protected void btnLogOff_Click(object sender, EventArgs e)
        {
            ExitFunc(0, 0);
        }
        protected void btnShutDown_Click(object sender, EventArgs e)
        {
            ExitFunc(1, 0);
        }
    }
}

Použitím príkazového riadku

 System.Diagnostics.Process.Start("shutdown", "/s");  

Parametre :

• /l logoff - odhlásiť
• /s shuts down - vypnúť windows
• /r restarts - reštartovať windows
• /h hibernates windows