C# code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApplication5
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Process(object sender, RoutedEventArgs e)
        {
            if ((string)(sender as Button).Content == "") { (sender as Button).Content = "X"; }
            else return;
            Random rnd = new Random();
            Button[] button = { LD, MD, RD , LM, MM, RM, LU, MU, RU};
            int random = 226;
            int G = 0;
            for (;;)
            {
                random = rnd.Next(9);
                if ((string)button[random].Content == "")
                {
                    button[random].Content = "0";
                    break;
                }
                else G++;
                if(G == 9) break;
            }
            if((string)LD.Content == "X" && (string)MD.Content == "X" && (string)RD.Content == "X") MessageBox.Show("Win");
            else if((string)LM.Content == "X" && (string)MM.Content == "X" && (string)RM.Content == "X") MessageBox.Show("Win");
            else if ((string)LU.Content == "X" && (string)MU.Content == "X" && (string)RU.Content == "X") MessageBox.Show("Win");

            else if ((string)LD.Content == "X" && (string)LM.Content == "X" && (string)LU.Content == "X") MessageBox.Show("Win");
            else if ((string)MD.Content == "X" && (string)MM.Content == "X" && (string)MU.Content == "X") MessageBox.Show("Win");
            else if ((string)RD.Content == "X" && (string)RM.Content == "X" && (string)RU.Content == "X") MessageBox.Show("Win");

            else if ((string)LU.Content == "X" && (string)MM.Content == "X" && (string)RD.Content == "X") MessageBox.Show("Win");
            else if ((string)RU.Content == "X" && (string)MM.Content == "X" && (string)LD.Content == "X") MessageBox.Show("Win");
            //
            //
            else if ((string)LD.Content == "0" && (string)MD.Content == "0" && (string)RD.Content == "0") MessageBox.Show("Lose");
            else if ((string)LM.Content == "0" && (string)MM.Content == "0" && (string)RM.Content == "0") MessageBox.Show("Lose");
            else if ((string)LU.Content == "0" && (string)MU.Content == "0" && (string)RU.Content == "0") MessageBox.Show("Lose");

            else if ((string)LD.Content == "0" && (string)LM.Content == "0" && (string)LU.Content == "0") MessageBox.Show("Lose");
            else if ((string)MD.Content == "0" && (string)MM.Content == "0" && (string)MU.Content == "0") MessageBox.Show("Lose");
            else if ((string)RD.Content == "0" && (string)RM.Content == "0" && (string)RU.Content == "0") MessageBox.Show("Lose");

            else if ((string)LU.Content == "0" && (string)MM.Content == "0" && (string)RD.Content == "0") MessageBox.Show("Lose");
            else if ((string)RU.Content == "0" && (string)MM.Content == "0" && (string)LD.Content == "0") MessageBox.Show("Lose");
        }
    }
}