How to check user status still login by using User.Identity.

In code bellow i make login for save username and password in cookies client if it is correct username and password

Actually what i need

I need not using cookies to save username and password In place of cookies i need to using User.Identity.IsAuthenticated in place of cookies

How to do that ?

code below working without any problem

I working in visual studio 2015 with asp.net mvc 4

what i try

for login view get I can restore username and password in login if username and password logged before(no problem in that)

public ActionResult Login()  
        {  
            UserAccount model = new UserAccount();  
            if (Request.Cookies["Login"] != null)  
            {  
                 model.UserName = Request.Cookies["Login"].Values["UserName"];  
                 model.Password = Request.Cookies["Login"].Values["Password"];  
            }  
            return View(model);  

From my code below i can login if username and password is correct also i can save username and password in cookies(no problem in that) .

public ActionResult Login(UserAccount user)  
        {  
            using (ContainerClass db = new ContainerClass())  
            {  
                var usr = db.userAccount.Where(u => u.UserName == user.UserName && u.Password == user.Password).FirstOrDefault();  
  
                if (usr != null)  
                {  
                    FormsAuthentication.SetAuthCookie(user.UserName, user.RememberMe);  
                    Session["UserID"] = user.UserID.ToString();  
                    Session["UserName"] = user.UserName.ToString();  
  
                    if (user.RememberMe)  
                    {  
                        HttpCookie cookie = new HttpCookie("Login");  
                        cookie.Values.Add("UserID", user.UserID.ToString());  
                        cookie.Values.Add("UserName", user.UserName);  
                        cookie.Values.Add("Password", user.Password);  
                        cookie.Expires = DateTime.Now.AddDays(15);  
                        Response.Cookies.Add(cookie);  
  
                    }  
  
                      return RedirectToAction("LoggedIn", "Account");  
  
                }  
                else  
                {  
                    ModelState.AddModelError("", "Username or Password is wrong");  
                }  
  
            }  
  
            return View(user);  
        }