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

Question

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);
        }