change screen using key empty gui

i want change the screen when i click in button login i don´t know how
i using this Tutorial https://www.youtube.com/watch?v=agt9-J9RPZ0
to make the game but i can put my game change the screen when i click in the button

i final found the way to change the screen when i click in the button the problem i can draw a new guiroot when i change screen
i don´t find where is the problem
my class splashscreen

this is my code
[code] using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Serialization;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using EmptyKeys.UserInterface.Generated;
using GameLibrary.Views;
using EmptyKeys.UserInterface.Controls;

    namespace CatRockets
    {
       
        public class SplashScreen : GameScreen
        {

           
            public Image Image;
        
            private UIRoot root;

            private BasicUIViewModel viewModel;
            public override void LoadContent()
            {
                base.LoadContent();
                root = new Root();
                // root.MaxHeight = 500;
                //root.MaxWidth = 600;

                // root.VerticalAlignment = VerticalAlignment.Bottom;
                viewModel = new BasicUIViewModel();
                root.DataContext = viewModel;
                Image.LoadContent();
            }

            public override void UnloadContent()
            {
                base.UnloadContent();
              Image.UnloadContent();
            }

            public override void Update(GameTime gameTime)
            {
                base.Update(gameTime);
               Image.Update(gameTime);
                root.UpdateInput(gameTime.ElapsedGameTime.TotalMilliseconds);
                root.UpdateLayout(gameTime.ElapsedGameTime.TotalMilliseconds);
                if (InputManager.Instance.KeyPressed(Keys.Enter,Keys.Z))
                    ScreenManager.Instance.ChangeScreens("TitleScreen");
                

            }

            public override void Draw(SpriteBatch spriteBatch)
            {
                Image.Draw(spriteBatch);
              

            }
        }
    }

[/code]
the code game class

using System;
using EmptyKeys.UserInterface;
using EmptyKeys.UserInterface.Controls;
using EmptyKeys.UserInterface.Generated;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using EmptyKeys.UserInterface.Input;
using GameLibrary;
using Microsoft.Xna.Framework.Storage;
using GameLibrary.Views;


namespace CatRockets
{
    /// <summary>
    /// This is the main type for your game.
    /// </summary>
    public class Game1 : Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;
        private int nativeScreenWidth;
        private int nativeScreenHeight;
        private bool result;

        private UIRoot root;
        
        private BasicUIViewModel viewModel;
        public Game1()
        {
            graphics = new GraphicsDeviceManager(this);
          graphics.DeviceCreated += graphics_DeviceCreated;
            graphics.PreparingDeviceSettings += graphics_PreparingDeviceSettings;
            Content.RootDirectory = "Content";
            IsMouseVisible = true;
        }

        /// <summary>
        /// Allows the game to perform any initialization it needs to before starting to run.
        /// This is where it can query for any required services and load any non-graphic
        /// related content.  Calling base.Initialize will enumerate through any components
        /// and initialize them as well.
        /// </summary>
        protected override void Initialize()
        {
           graphics.PreferredBackBufferWidth = (int)ScreenManager.Instance.Dimension.X;
           graphics.PreferredBackBufferHeight = (int)ScreenManager.Instance.Dimension.Y;
            graphics.ApplyChanges();
            // TODO: Add your initialization logic here

            base.Initialize();
        }
        void graphics_DeviceCreated(object sender, EventArgs e)
        {
            Engine engine = new MonoGameEngine(GraphicsDevice, nativeScreenWidth, nativeScreenHeight);
        }
        private void graphics_PreparingDeviceSettings(object sender, PreparingDeviceSettingsEventArgs e)
        {
            nativeScreenWidth = graphics.PreferredBackBufferWidth;
            nativeScreenHeight = graphics.PreferredBackBufferHeight;

            graphics.PreferredBackBufferWidth = 800;
            graphics.PreferredBackBufferHeight = 600;
            graphics.PreferMultiSampling = true;
            graphics.GraphicsProfile = GraphicsProfile.HiDef;
            graphics.SynchronizeWithVerticalRetrace = true;
            graphics.PreferredDepthStencilFormat = DepthFormat.Depth24Stencil8;
            e.GraphicsDeviceInformation.PresentationParameters.MultiSampleCount = 16;
        }
       
       /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        protected override void LoadContent()
        {
            
            SpriteFont font = Content.Load<SpriteFont>("Segoe_UI_15_Bold");
            FontManager.DefaultFont = Engine.Instance.Renderer.CreateFont(font);
            Viewport viewport = GraphicsDevice.Viewport;
            root = new Root();
         // root.MaxHeight = 500;
            //root.MaxWidth = 600;
           
           // root.VerticalAlignment = VerticalAlignment.Bottom;
            viewModel = new BasicUIViewModel();



            viewModel.ButtonCommand = new RelayCommand(new Action<object>(Login));
            //  object login = viewModel.ButtonCommand;
            //lo
            viewModel.Options = new RelayCommand(new Action<object>(Options));
            viewModel.Exit = new RelayCommand(new Action<object>(ExitGame));

            //root.RenderPosition(200,300);



            root.DataContext = viewModel;
           
            FontManager.Instance.LoadFonts(Content);
         


            spriteBatch = new SpriteBatch(GraphicsDevice);
             ScreenManager.Instance.GraphicsDevice = GraphicsDevice;
             ScreenManager.Instance.SpriteBatch = spriteBatch;
             ScreenManager.Instance.LoadContent(Content);
           

            // TODO: use this.Content to load your game content here
        }
       
        /// <summary>
        /// UnloadContent will be called once per game and is the place to unload
        /// game-specific content.
        /// </summary>
        protected override void UnloadContent()

        {
         ScreenManager.Instance.UnloadContent();            // TODO: Unload any non ContentManager content here
        }

        /// <summary>
        /// Allows the game to run logic such as updating the world,
        /// checking for collisions, gathering input, and playing audio.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Update(GameTime gameTime)
        {
           

            //          
            ScreenManager.Instance.Update(gameTime);
            // TODO: Add your update logic here
           root.UpdateInput(gameTime.ElapsedGameTime.TotalMilliseconds);
            root.UpdateLayout(gameTime.ElapsedGameTime.TotalMilliseconds);
            base.Update(gameTime);
        }

        /// <summary>
        /// This is called when the game should draw itself.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Draw(GameTime gameTime)
        {
           GraphicsDevice.Clear(Color.CornflowerBlue);
           
               
            
            root.Draw(gameTime.ElapsedGameTime.TotalMilliseconds);

            if (result == true)
            {
                GraphicsDevice.Clear(Color.CornflowerBlue);
                spriteBatch.Begin();
                ScreenManager.Instance.Draw(spriteBatch);
              //  root.Unloaded+=root.Unloaded;
                // TODO: Add your drawing code here
                spriteBatch.End();
            }
            /*  */
            base.Draw(gameTime);
        }
        private void Login(object obj)
        {

            System.Console.Write("object " + obj);

            // if(obj !=null)

            string username = viewModel.TextBoxText.ToString();
            string password = viewModel.Password.ToString();

            System.Console.Write("Username: " + username + " " + "password " + password + "\n");

            if (username == string.Empty && password == string.Empty)
            {
                MessageBox.Show("Utilizador e Senha estao vazios ", null, false);
                viewModel.TextBoxText = string.Empty;
                viewModel.Password = string.Empty;
            }
          else if (username == string.Empty)
            {
                MessageBox.Show("Utilizador esta vazio", null, false);
                viewModel.TextBoxText = string.Empty;
                viewModel.Password = string.Empty;

            }
            else if (password == string.Empty)
            {
                MessageBox.Show("Senha esta vazio", null, false);
                viewModel.TextBoxText = string.Empty;
                viewModel.Password = string.Empty;

            }
           
            else 
             {
        
                result = true;
            

                        }

              
        }
        private void ExitGame(object obj)

        {
            
            System.Windows.Forms.DialogResult resultado =System.Windows.Forms.MessageBox.Show("Quer Sair do Jogo", "Aviso", System.Windows.Forms.MessageBoxButtons.YesNo, System.Windows.Forms.MessageBoxIcon.Information);

            switch (resultado)

            {
                case System.Windows.Forms.DialogResult.No:

                    break;

             
              

                case System.Windows.Forms.DialogResult.Yes: Exit();

                    break;

     

            }





        }
        private void Options(object obj)

        {

            System.Console.Write("object " + obj);

            // if(obj !=null)


            //   Password.ToString();
            if (obj == null)
            {
         
               root = new options();
               
        
            }


        }
        
    }
}