public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            //показывает папку
            //if (folderBrowserDialog1.ShowDialog() == DialogResult.OK)
            //{
            //    textBox1.Text = folderBrowserDialog1.SelectedPath;
            //    pictureBox1.Image = ShellFileInfo.GetIcon(textBox1.Text).ToBitmap();
            //}

            // показывает файл
            //if (openFileDialog1.ShowDialog() == DialogResult.OK)
            //{
            //    textBox1.Text = openFileDialog1.FileName;
            //    pictureBox1.Image = ShellFileInfo.GetIcon(textBox1.Text).ToBitmap();
            //}

            //показывает диск аки - C:
            pictureBox1.Image = ShellFileInfo.GetIcon(textBox1.Text).ToBitmap();
        }
    }
    public static class ShellFileInfo
    {
        private const uint SHGFI_ICON = 0x100;
        private const uint SHGFI_LARGEICON = 0x0;

        static class NativeMethods
        {
            [DllImport("shell32.dll", SetLastError = true)]
            public static extern IntPtr SHGetFileInfo(string pszPath, uint dwFileAttributes, ref SHFILEINFO psfi, uint cbSizeFileInfo, uint uFlags);

            [DllImport("user32.dll")]
            public static extern int DestroyIcon(IntPtr Icon);
        }

        [StructLayout(LayoutKind.Sequential)]
        struct SHFILEINFO
        {
            public IntPtr hIcon;
            public IntPtr iIcon;
            public uint dwAttributes;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
            public string szDisplayName;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
            public string szTypeName;
        };



        public static Icon GetIcon(string fileName)
        {
            var shinfo = new SHFILEINFO();
            if (NativeMethods.SHGetFileInfo(fileName, 0, ref shinfo, (uint)Marshal.SizeOf(shinfo), SHGFI_ICON | SHGFI_LARGEICON) == IntPtr.Zero)
                Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
            var tmp = Icon.FromHandle(shinfo.hIcon);
            try
            {
                var res = (Icon)tmp.Clone();
                tmp.Dispose();
                NativeMethods.DestroyIcon(shinfo.hIcon);
                return res;
            }
            catch
            { }
            return null;
        }




    }