Error CS0201

Hi, I've used the script from UnifyCommunity to create a pause menu in-game the only problem is that my character will still centeralise it's viewing wherever the mouse is while it is in the menu, I therefore need to 'freeze' the X & Y Rotation when the "Escape" button is pressed and have it 'unfreeze' when the "escape" button is clicked again - for ease of answer I have included all 300 lines of code and made the section I have edited bold so you can try to understand why I am getting this error code.

This is the section I have attempted to edit, giving me the error code:

  if (Input.GetKeyDown("escape")) 
  {
      ***RigidbodyConstraints.FreezeRotationY;***
      switch (currentPage) 
      {
      case Page.None: 
          PauseGame(); 
          break;
          
      case Page.Main: 
          if (!IsBeginning()) 
              UnPauseGame(); 
          break;
          
      default: 
          currentPage = Page.Main;
          break;
      }
  }

}

This is the full code that I am using:

{

 public GUISkin skin;
 
 private float gldepth = -0.5f;
 private float startTime = 0.1f;
 
 public Material mat;
 
 private long tris = 0;
 private long verts = 0;
 private float savedTimeScale;
 
 private bool showfps;
 private bool showtris;
 private bool showvtx;
 private bool showfpsgraph;
 
 public Color lowFPSColor = Color.red;
 public Color highFPSColor = Color.green;
 
 public int lowFPS = 30;
 public int highFPS = 50;
 
 public GameObject start;
 
 public string url = "unity.html";
 
 public Color statColor = Color.yellow;
 
 public string[] credits= {
     "A Fugu Games Production",
     "Programming by Phil Chu",
     "Fugu logo by Shane Nakamura Designs",
     "Copyright (c) 2007-2008 Technicat, LLC"} ;
 public Texture[] crediticons;
 
 public enum Page {
     None,Main,Options,Credits
 }
 
 private Page currentPage;
 
 private float[] fpsarray;
 private float fps;
 
 private int toolbarInt = 0;
 private string[]  toolbarstrings =  {"Audio","Graphics","Stats","System"};
 
 
 void Start() {
     fpsarray = new float[Screen.width];
     Time.timeScale = 1;

 }
 
 void OnPostRender() {
     if (showfpsgraph && mat != null) {
         GL.PushMatrix ();
         GL.LoadPixelMatrix();
         for (var i = 0; i < mat.passCount; ++i)
         {
             mat.SetPass(i);
             GL.Begin( GL.LINES );
             for (int x=0; x < fpsarray.Length; ++x) {
                 GL.Vertex3(x, fpsarray[x], gldepth);
             }
             GL.End();
         }
         GL.PopMatrix();
         ScrollFPS();
     }
 }
 
 void ScrollFPS() {
     for (int x = 1; x < fpsarray.Length; ++x) {
         fpsarray[x-1]=fpsarray[x];
     }
     if (fps < 1000) {
         fpsarray[fpsarray.Length - 1]=fps;
     }
 }
 
 static bool IsDashboard() {
     return Application.platform == RuntimePlatform.OSXDashboardPlayer;
 }
 
 static bool IsBrowser() {
     return (Application.platform == RuntimePlatform.WindowsWebPlayer ||
             Application.platform == RuntimePlatform.OSXWebPlayer);
 }
 
 void LateUpdate () {
     if (showfps || showfpsgraph) {
         FPSUpdate();
     }
     
     if (Input.GetKeyDown("escape")) 
     {
         ***RigidbodyConstraints.FreezeRotationY;***
         switch (currentPage) 
         {
         case Page.None: 
             PauseGame(); 
             break;
             
         case Page.Main: 
             if (!IsBeginning()) 
                 UnPauseGame(); 
             break;
             
         default: 
             currentPage = Page.Main;
             break;
         }
     }
 }
 
 void OnGUI () {
     if (skin != null) {
         GUI.skin = skin;
     }
     ShowStatNums();
     ShowLegal();
     if (IsGamePaused()) {
         GUI.color = statColor;
         switch (currentPage) {
         case Page.Main: MainPauseMenu(); break;
         case Page.Options: ShowToolbar(); break;
         case Page.Credits: ShowCredits(); break;
         }
     }   
 }
 
 void ShowLegal() {
     if (!IsLegal()) {
         GUI.Label(new Rect(Screen.width-100,Screen.height-20,90,20),
                   "jdonavan.com");
     }
 }
 
 bool IsLegal() {
     return !IsBrowser() || 
         Application.absoluteURL.StartsWith("http://www.jdonavan.com/") ||
             Application.absoluteURL.StartsWith("http://jdonavan.com/");
     
 }
 
 void ShowToolbar() {
     BeginPage(300,300);
     toolbarInt = GUILayout.Toolbar (toolbarInt, toolbarstrings);
     switch (toolbarInt) {
     case 0: VolumeControl(); break;
     case 3: ShowDevice(); break;
     case 1: Qualities(); QualityControl(); break;
     case 2: StatControl(); break;
     }
     EndPage();
 }
 
 void ShowCredits() {
     BeginPage(300,300);
     foreach(string credit in credits) {
         GUILayout.Label(credit);
     }
     foreach( Texture credit in crediticons) {
         GUILayout.Label(credit);
     }
     EndPage();
 }
 
 void ShowBackButton() {
     if (GUI.Button(new Rect(20, Screen.height - 50, 50, 20),"Back")) {
         currentPage = Page.Main;
     }
 }
 
 void ShowDevice() {
     GUILayout.Label("Unity player version "+Application.unityVersion);
     GUILayout.Label("Graphics: "+SystemInfo.graphicsDeviceName+" "+
                     SystemInfo.graphicsMemorySize+"MB\n"+
                     SystemInfo.graphicsDeviceVersion+"\n"+
                     SystemInfo.graphicsDeviceVendor);
     GUILayout.Label("Shadows: "+SystemInfo.supportsShadows);
     GUILayout.Label("Image Effects: "+SystemInfo.supportsImageEffects);
     GUILayout.Label("Render Textures: "+SystemInfo.supportsRenderTextures);
 }
 
 void Qualities() {
     switch (QualitySettings.GetQualityLevel()) 
     {
     case 0:
         GUILayout.Label("Fastest");
         break;
     case 1:
         GUILayout.Label("Fast");
         break;
     case 2:
         GUILayout.Label("Simple");
         break;
     case 3:
         GUILayout.Label("Good");
         break;
     case 4:
         GUILayout.Label("Beautiful");
         break;
     default:
         GUILayout.Label("Fantastic");
         break;
     }
 }
 
 void QualityControl() {
     GUILayout.BeginHorizontal();
     if (GUILayout.Button("Decrease")) {
         QualitySettings.DecreaseLevel();
     }
     if (GUILayout.Button("Increase")) {
         QualitySettings.IncreaseLevel();
     }
     GUILayout.EndHorizontal();
 }
 
 void VolumeControl() {
     GUILayout.Label("Volume");
     AudioListener.volume = GUILayout.HorizontalSlider(AudioListener.volume, 0, 1);
 }
 
 void StatControl() {
     GUILayout.BeginHorizontal();
     showfps = GUILayout.Toggle(showfps,"FPS");
     showtris = GUILayout.Toggle(showtris,"Triangles");
     showvtx = GUILayout.Toggle(showvtx,"Vertices");
     showfpsgraph = GUILayout.Toggle(showfpsgraph,"FPS Graph");
     GUILayout.EndHorizontal();
 }
 
 void FPSUpdate() {
     float delta = Time.smoothDeltaTime;
     if (!IsGamePaused() && delta !=0.0) {
         fps = 1 / delta;
     }
 }
 
 void ShowStatNums() {
     GUILayout.BeginArea( new Rect(Screen.width - 100, 10, 100, 200));
     if (showfps) {
         string fpsstring= fps.ToString ("#,##0 fps");
         GUI.color = Color.Lerp(lowFPSColor, highFPSColor,(fps-lowFPS)/(highFPS-lowFPS));
         GUILayout.Label (fpsstring);
     }
     if (showtris || showvtx) {
         GetObjectStats();
         GUI.color = statColor;
     }
     if (showtris) {
         GUILayout.Label (tris+"tri");
     }
     if (showvtx) {
         GUILayout.Label (verts+"vtx");
     }
     GUILayout.EndArea();
 }
 
 void BeginPage(int width, int height) {
     GUILayout.BeginArea( new Rect((Screen.width - width) / 2, (Screen.height - height) / 2, width, height));
 }
 
 void EndPage() {
     GUILayout.EndArea();
     if (currentPage != Page.Main) {
         ShowBackButton();
     }
 }
 
 bool IsBeginning() {
     return (Time.time < startTime);
 }
 
 
 void MainPauseMenu() {
     BeginPage(200,200);
     if (GUILayout.Button (IsBeginning() ? "Play" : "Continue")) {
         UnPauseGame();
         
     }
     if (GUILayout.Button ("Options")) {
         currentPage = Page.Options;
     }
     if (GUILayout.Button ("Credits")) {
         currentPage = Page.Credits;
     }
     if (IsBrowser() && !IsBeginning() && GUILayout.Button ("Restart")) {
         Application.OpenURL(url);
     }
     EndPage();
 }
 
 void GetObjectStats() {
     verts = 0;
     tris = 0;
     GameObject[] ob = FindObjectsOfType(typeof(GameObject)) as GameObject[];
     foreach (GameObject obj in ob) {
         GetObjectStats(obj);
     }
 }
 
 void GetObjectStats(GameObject obj) {
     Component[] filters;
     filters = obj.GetComponentsInChildren<MeshFilter>();
     foreach( MeshFilter f  in filters )
     {
         tris += f.sharedMesh.triangles.Length/3;
         verts += f.sharedMesh.vertexCount;
     }
 }
 
 void PauseGame() {
     savedTimeScale = Time.timeScale;
     Time.timeScale = 0;
     AudioListener.pause = true;
     
     currentPage = Page.Main;
 }
 
 void UnPauseGame() {
     Time.timeScale = savedTimeScale;
     AudioListener.pause = false;
     currentPage = Page.None;
     
     if (IsBeginning() && start != null) {
         start.SetActive(true);
     }
 }
 
 bool IsGamePaused() {
     return (Time.timeScale == 0);
 }
 
 void OnApplicationPause(bool pause) {
     if (IsGamePaused()) {
         AudioListener.pause = true;
     }
 }

}