ASP.net proper login - logout classes - control login status Would you have any suggestions improvements for the below functions classes ?

Ok here how do i make a registered member login

    HttpCookie LoginInfo = new HttpCookie("LoginInfo");
    LoginInfo.Values["UserName"] = srUserName;
    LoginInfo.Values["Password"] = srPassword;
    LoginInfo.Values["selectedLanguage"] = srSelectedLanguage;
    Response.Cookies.Add(LoginInfo);


Here how do i check visitor is logged in or not

public static void controlOfLoginStatus()
{
    string srQuery = "";
    string srUserName = "";
    string srPassword = "";
    string srLang = "";

    if (HttpContext.Current.Session["UserId"] == null)
    {
        if (HttpContext.Current.Request.Cookies["LoginInfo"] != null)
        {
            try
            {
                srUserName = HttpContext.Current.Request.Cookies["LoginInfo"]["UserName"].ToString();
                srPassword = HttpContext.Current.Request.Cookies["LoginInfo"]["Password"].ToString();
                srLang = HttpContext.Current.Request.Cookies["LoginInfo"]["selectedLanguage"].ToString();
            }
            catch
            {

            }
        }
        string srUserIdTemp = csPublicFunctions.ReturnUserIdUsernamePassword(srUserName, srPassword);
        if (srUserIdTemp == "0")
        {
            HttpContext.Current.Session.Clear();
            HttpContext.Current.Session.Abandon();
            HttpContext.Current.Response.Redirect("Login");
        }
        else
        {
            csPublicFunctions.insertIntoOnlineUsers(srUserIdTemp, HttpContext.Current.Session.SessionID);
            HttpContext.Current.Session["UserId"] = srUserIdTemp;
            if (HttpContext.Current.Session["lang"] == null)
                HttpContext.Current.Session["lang"] = srLang;
        }
    }

    srQuery = "SELECT UserId " +
     " FROM BannedUsers" +
     " WHERE UserId = " + HttpContext.Current.Session["UserId"].ToString();
    using (DataTable dtTemp = DbConnection.db_Select_DataTable(srQuery))
    {
        if (dtTemp.Rows.Count &gt; 0)
        {
            HttpContext.Current.Response.Redirect("exit.aspx");
        }
    }
}


Here how do i log-out

public static void exitLogout()
{
    string srQuery = "delete from OnlineUsers where UserId=" + HttpContext.Current.Session["UserId"].ToString();
    DbConnection.db_Update_Delete_Query(srQuery);

    try
    {
        HttpContext.Current.Session["UserId"] = "0";
        HttpContext.Current.Session.Clear();
        HttpContext.Current.Session.Abandon();
    }
    catch
    {

    }

    try
    {
        HttpCookie LoginInfo = new HttpCookie("LoginInfo");
        LoginInfo.Values["UserName"] = "21412zxcvzxc343245243vvc";
        LoginInfo.Values["Password"] = "21412zxcvzxc343245243vvc";
        LoginInfo.Values["selectedLanguage"] = "en";
        HttpContext.Current.Response.Cookies.Add(LoginInfo);
    }
    catch
    {            
    }
}


csPublicFunctions.ReturnUserIdUsernamePassword uses parametrized queries so no possible risk of SQL injection
In addition to losing the hungarian notation there are a few things worth mentioning:


Don't use try-catch construction with empty 'catch' clause. It is almost always a bad idea to hide an exception if it was thrown. 
It would be better to check explicitly if the key is in the collection using appropriate methods. BTW exception handling is quite expensive speedwise and explicit checking will work faster.
Try to refactor your controlOfLoginStatus() method into several distinct functions with more meaningful purpose.
Refactor your database code into separate class.
Use parameterized queries while working with database. It will save you from sql injections and it will make your queries run faster.