Смена даты и времени

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.Diagnostics;
using System.Security.Principal;
 
 
 
namespace Дата_и_Время_на_ПК
    
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            label1.Text = "";
            label2.Text = "";
            timer1.Enabled = true;
            timer1.Interval = 1000;
        }
        
                   
                private void timer1_Tick(object sender, EventArgs e)
                    
        {
            label1.Text = DateTime.Now.ToLongDateString();
            label2.Text = DateTime.Now.ToLongTimeString();
        }
 
       
    }
}

[StructLayout(LayoutKind.Sequential)]
public struct SYSTEMTIME
{
    public short wYear;
    public short wMonth;
    public short wDayOfWeek;
    public short wDay;
    public short wHour;
    public short wMinute;
    public short wSecond;
    public short wMilliseconds;
}
 
[DllImport("kernel32.dll", SetLastError = true)]
public static extern bool SetSystemTime(ref SYSTEMTIME st);
 
private void ChangeData()
{
    SYSTEMTIME st = new SYSTEMTIME();
    st.wYear = 2009; 
    st.wMonth = 1;
    st.wDay = 1;
    st.wHour = 0;
    st.wMinute = 0;
    st.wSecond = 0;
 
    SetSystemTime(ref st);
}