Password is not updated in database when changed by user

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Change_Password : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }


    public string UsrID
    { get; set; }



    private void ShowResult(string _msg)
    {
        divmsg2.Visible = true;
        ltrmsg2.Text = _msg;
    }


    protected void btnSubmit_Click(object sender, EventArgs e)
    {
        try
        {


            if (String.IsNullOrEmpty(TxtOldPass.Text) || String.IsNullOrEmpty(TxtNewPass.Text) || String.IsNullOrEmpty(TxtConfPass.Text))
            {
                ShowResult("Please fill in the fields");
            }

            else
            {

                if (Context.User.Identity.IsAuthenticated)
                {

                    usermasterDataContext context = new usermasterDataContext();
                    var data = context.passwords.Single(m => m.UsrPassword == TxtOldPass.Text);
                    var UID = context.passwords.Where(i => i.UsrPassword==TxtOldPass.Text).Select(i => i.ID).ToList();
                   
                    foreach (int i in UID)
                    {
                        UsrID = i.ToString();
                    }
                    string oldpass = data.UsrPassword.ToString();
                    string newpass = TxtNewPass.Text;
                    string confpass = TxtConfPass.Text;

                    if (oldpass == TxtOldPass.Text)
                    {
                        var data2 = (from p in context.passwords
                                     where p.ID == Convert.ToInt64(UsrID)
                                     select p).Single();

                        data2.UsrPassword = newpass.ToString();
                        context.SubmitChanges();
                     
                        ShowResult("Password Changed Successfully");
                        //Panel1.Visible = false;
                       
                    }
                    else
                    {
                        ShowResult("Old password does not match");
                        return;
                    }
                    if (TxtConfPass.Text != TxtNewPass.Text)
                    {
                        ShowResult("New Password and Confirm Password do not match");
                        return;
                    }
                }

            }
        }

        catch
        {
            ShowResult("Some error occured. Please try again later!");
        }

        finally
        {
            TxtOldPass.Text = "";
            TxtNewPass.Text = "";
            TxtConfPass.Text = "";
        }
    }
    protected void btnCancel_Click(object sender, EventArgs e)
    {
        Panel1.Visible = false;
        LinkButton lb = (LinkButton)this.Parent.FindControl("lnkChangepwd");
        lb.Visible = true;
    }
}