public partial class Form1 : Form
    {
        public uint VK_RETURN = 0x0D;
        public int WM_SETTEXT = 0x000C;
        public int WM_KEYDOWN = 0x100;
        public Form1()
        {
            InitializeComponent();
        }
        private void button1_Click(object sender, EventArgs e)
        {
            var iResult = new List<IntPtr>();
            IntPtr hwnd = FindWindow(null, "DWS");

          //循环窗体下的所有控件
            EnumChildWindows(
            hwnd,
            (h, l) =>
            {
                IntPtr f1 = FindWindowEx(h, IntPtr.Zero, "WindowsForms10.EDIT.app.0.34f5582_r12_ad1", null);
                if (f1 == IntPtr.Zero)
                    return true;
                else
                {
                    iResult.Add(f1);
                    return true;
                }
            },
            0);
            var indexs = int.Parse( textBox1.Text);

             SendMessage(iResult.Skip(indexs).Take(1).First(), WM_SETTEXT, IntPtr.Zero, new StringBuilder("00050B80"));
              //回车键
             SendMessage(iResult.Skip(indexs).Take(1).First(), WM_KEYDOWN, VK_RETURN, 0);
            //设置文字
        }


        [DllImport("User32.dll", EntryPoint = "FindWindow")]
        public extern static IntPtr FindWindow(string lpClassName, string lpWindowName);
        [DllImport("user32.dll")]
        private static extern Int32 SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, StringBuilder lParam);
        [DllImport("user32.dll", EntryPoint = "SendMessage")]
        public static extern int SendMessage(IntPtr hwnd, int wMsg, uint wParam, uint lParam);
        [DllImport("user32.dll", EntryPoint = "FindWindowEx", CharSet = CharSet.Auto)]
        private extern static IntPtr FindWindowEx(IntPtr parent, IntPtr child, string classname, string captionName);

        public delegate bool CallBack(IntPtr hwnd, int lParam);
        [DllImport("user32.DLL")]
        public static extern int EnumChildWindows(IntPtr hWndParent, CallBack lpfn, int lParam);
    }