password can not update in asp.net

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web.Security;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls.WebParts;
using System.Data.SqlClient;

public partial class Admin_Changepaswword : System.Web.UI.Page
{

   
        string strConnString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
        string str = null;
        SqlCommand com;
        byte up;
        


    protected void Button1_Click(object sender, EventArgs e)
    {
        SqlConnection con = new SqlConnection(strConnString);
            con.Open();
            str = "select * from registration ";
            com = new SqlCommand(str, con);
            SqlDataReader reader = com.ExecuteReader();

            while (reader.Read())
            {
                if (txtcnfpass.Text == reader["password"].ToString())
                {
                    up = 0;
                }
            }
            reader.Close();
            con.Close();
            if (up == 0)
            {
                con.Open();
                str = "update login set password="+txtnewpass.Text+" where id='1'";
                com = new SqlCommand(str, con);
                com.Parameters.Add(new SqlParameter("@Password", SqlDbType.VarChar, 50));
                com.Parameters["@Password"].Value = txtnewpass.Text;
               // com.ExecuteNonQuery();
                con.Close();
                Label1.Text = "Password changed Successfully";
            }
            else
            {
                Label1.Text = "Please enter correct Current password";
            }
        } 
    }