try to Perform reset to my program But without success

i try to Perform reset to my C# program like this:

System.Windows.Forms.Application.Restart();

also i have in the Program class this To ensure that there is only one instance

 [STAThread]
        static void Main()
        {
            if (Process.GetProcessesByName(Process.GetCurrentProcess().ProcessName).Length > 1)
            {
                MessageBox.Show("the program is runing", "attention", 0, MessageBoxIcon.Hand);
                return;
            }
            else
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Main());

             }
}

The problem that when I run the program and Perform reset

System.Windows.Forms.Application.Restart(); 

i got message that the program is running Or nothing happens at all.

thanks