Prevent Multiple Instances for Windows Application in .NET

This code is used to prevent Multiple instances of same application.I googled a day for this.

//Add these References
using System.Threading;
using System.Reflection;
using System.Runtime.InteropServices;

Simple way to Prevent Multiple Instance.Write this code in Program.cs,

Application.Run(new Form1());
GC.KeepAlive(Mut);
}

This is the another way,

[STAThread]
static void Main()
{
bool NewWindow;
Mutex Mut = new Mutex(true, "YourApplicationName", out NewWindow);
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
if (!NewWindow)
{
IntPtr hWnd = FindWindow("WindowsForms10.Window.8.app3", "YourApplicationName");
if (hWnd != IntPtr.Zero)
{
WINDOWPLACEMENT placement = new WINDOWPLACEMENT();
placement.length = Marshal.SizeOf(placement);

GetWindowPlacement(hWnd, ref placement);
if (placement.showCmd != SW_NORMAL)
{
placement.showCmd = SW_RESTORE;

SetWindowPlacement(hWnd, ref placement);
SetForegroundWindow(hWnd);
}
}
return;
}
Application.Run(new Form1());
GC.KeepAlive(Mut);
}

private const int SW_NORMAL = 1;
private const int SW_RESTORE = 9;

[DllImport("User32", EntryPoint = "FindWindow")]
static extern IntPtr FindWindow(string className, string windowName);

[DllImport("User32", EntryPoint = "SendMessage")]
private static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

[DllImport("User32", EntryPoint = "SetForegroundWindow")]
private static extern bool SetForegroundWindow(IntPtr hWnd);

[DllImport("User32", EntryPoint = "SetWindowPlacement")]
private static extern bool SetWindowPlacement(IntPtr hWnd, [In] ref WINDOWPLACEMENT lpwndpl);

[DllImport("User32", EntryPoint = "GetWindowPlacement")]
private static extern bool GetWindowPlacement(IntPtr hWnd, [In] ref WINDOWPLACEMENT lpwndpl);

private struct POINTAPI
{
public int x;
public int y;
}

private struct RECT
{
public int left;
public int top;
public int right;
public int bottom;
}

private struct WINDOWPLACEMENT
{
public int length;
public int flags;
public int showCmd;
public POINTAPI ptMinPosition;
public POINTAPI ptMaxPosition;
public RECT rcNormalPosition;
}