code is not working plz check this

DataBaseClass dbClass = new DataBaseClass();
    public DataTable dt;
    protected void Page_Load(object sender, EventArgs e)
    {
    }
    public void GetUserDetails(int id)
    {
        string getUserDetail = "Select ID,Email,Name,Country,Convert(varchar (20), RegisterDate, 106) RegisterDate,Convert(varchar (20), LastLogin, 106) LastLogin ,Description,ImageName FROM [User] where Id='" + id + "'";
        dt = dbClass.ConnectDataBaseReturnDT(getUserDetail);
        if (dt.Rows.Count > 0)
        {
           Image1.ImageUrl = "~/UserImage/" + dt.Rows[11]["ImageName"].ToString();
        }

DataBaseClass dbClass = new DataBaseClass();
    public DataTable dt;
    protected void Page_Load(object sender, EventArgs e)
    {
    }
    protected void OnAuthenticate(object sender, AuthenticateEventArgs e)
    {
        bool Authenticated = false;
        CheckBox chBox = (CheckBox)ctlLogin.FindControl("RememberMe");
        Authenticated = UserAuthenticate(ctlLogin.UserName, ctlLogin.Password);
        e.Authenticated = Authenticated;
        if (Authenticated == true)
        {
            if (chBox.Checked == true)
            {
                Response.Cookies["RFriend_Email"].Value = ctlLogin.UserName;
                Response.Cookies["RFriend_PWD"].Value = ctlLogin.Password;
                Response.Cookies["RFriend_UID"].Value = Session["UserId"].ToString();
                Response.Cookies["RFriend_Email"].Expires = DateTime.Now.AddMonths(3);
                Response.Cookies["RFriend_PWD"].Expires = DateTime.Now.AddMonths(3);
                Response.Cookies["RFriend_UID"].Expires = DateTime.Now.AddMonths(3);
            }
            Response.Redirect("UserDetails.aspx?Id=" + Session["UserId"].ToString());
        }
    }
    private bool UserAuthenticate(string UserName, string Password)
    {
        bool boolReturnValue = false;
        //--------------------------------
        //Check UserID From Config File
        if (UserName == "Rahul" && Password == "Saxena")
        {
            boolReturnValue = true;
            return boolReturnValue;
        }
        else
        {
            //--------------------------------
            dt = new DataTable();
            SqlConnection con=new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\omar\Documents\Visual Studio 2005\WebSites\WebSite8\App_Data\Database.mdf;Integrated Security=True;User Instance=True");
            string chkUser = "Select * FROM [User] where Email='" + UserName + "' AND Password='" + Password + "'";
            dt = dbClass.ConnectDataBaseReturnDT(chkUser);
            if (dt.Rows.Count > 0)
            {
                boolReturnValue = true;
                Session["UserId"] = dt.Rows[0]["Id"].ToString();
                SqlCommand cmd = new SqlCommand("UPDATE [User] SET LastLogon = GETDATE() where Id= @UserId", con);
                SqlParameter param = new SqlParameter();
                param.ParameterName = "@UserId";
                param.Value = Session["UserId"];
                cmd.Parameters.Add(param);
                
            }
            return boolReturnValue;
        }
    }

ID                int
Email             primarykey varchar(250)     
Password          varchar(250)
Name              varchar(250)                  
Country           varchar(250)
Gender            varchar(250)
Year              varchar(250) 
Date              varchar(250)
Month             varchar(250)
RegisterDate      datetime                   allownulls 
LastLogin         datetime                   allownulls
Description       varchar(50)
ImageName         varchar(1000)

SqlDataAdapter da;
    SqlConnection con;
    SqlCommand cmd = new SqlCommand();
    DataSet ds = new DataSet();
    DataTable dt = new DataTable();
    public DataBaseClass()
	{
		//
		// TODO: Add constructor logic here
		//
	}
    public void ConnectDataBaseToInsert(string Query)
    {
        con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\omar\Documents\Visual Studio 2005\WebSites\WebSite8\App_Data\Database.mdf;Integrated Security=True;User Instance=True");
        cmd.CommandText = Query;
        cmd.Connection = con;
        da = new SqlDataAdapter(cmd);
        con.Open();
        cmd.ExecuteNonQuery();
        con.Close();
    }
    public DataSet ConnectDataBaseReturnDS(string Query)
    {
        ds = new DataSet();
        con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\omar\Documents\Visual Studio 2005\WebSites\WebSite8\App_Data\Database.mdf;Integrated Security=True;User Instance=True");
        cmd.CommandText = Query;
        cmd.Connection = con;
        da = new SqlDataAdapter(cmd);
        da.Fill(ds);
        con.Open();
        cmd.ExecuteNonQuery();
        con.Close();
        return ds;
    }
    public DataTable ConnectDataBaseReturnDT(string Query)
    {
        dt = new DataTable();
        con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\omar\Documents\Visual Studio 2005\WebSites\WebSite8\App_Data\Database.mdf;Integrated Security=True;User Instance=True");
        cmd.CommandText = Query;
        cmd.Connection = con;
        da = new SqlDataAdapter(cmd);
        da.Fill(dt);
        con.Open();
        cmd.ExecuteNonQuery();//error is here 
        con.Close();
        return dt;
    }