Изменить отображение скрытых файлов и папок

using System.Runtime.InteropServices;
using Microsoft.Win32;
// ....
using (RegistryKey advKey = Registry.CurrentUser.OpenSubKey(@"Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced", true))
{
    advKey.SetValue("Hidden", 1);
}
// Отправляем широковещательное уведомление о сделанном изменении
SendMessageTimeout(
    HWND_BROADCAST,
    WM_SETTINGCHANGE,
    IntPtr.Zero,
    new IntPtr(1),
    SendMessageTimeoutFlags.SMTO_NORMAL,
    1000,
    out dummy
);
// ....
readonly static IntPtr HWND_BROADCAST = new IntPtr(0xFFFF);
const uint WM_SETTINGCHANGE = 0x001A;
 
[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
public static extern IntPtr SendMessageTimeout(
    IntPtr windowHandle,
    uint msg,
    IntPtr wParam,
    IntPtr lParam,
    SendMessageTimeoutFlags flags,
    uint timeout, // In milliseconds
    out IntPtr result
);
 
[Flags]
public enum SendMessageTimeoutFlags
{
    ///<summary>The calling thread is not prevented from processing other requests while waiting for the function to return.</summary>
    SMTO_NORMAL = 0x00,
 
    ///<summary>Prevents the calling thread from processing any other requests until the function returns.</summary>
    SMTO_BLOCK = 0x01,
 
    ///<summary>The function returns without waiting for the time-out period to elapse if the receiving thread appears to not respond or "hangs."</summary>
    SMTO_ABORTIFHUNG = 0x02,
 
    ///<summary>The function does not enforce the time-out period as long as the receiving thread is processing messages.</summary>
    SMTO_NOTIMEOUTIFNOTHUNG = 0x08,
 
    ///<summary>The function does not enforce the time-out period as long as the receiving thread is processing messages.</summary>
    SMTO_ERRORONEXIT = 0x20
}