cannot read gridview control.

[jugnu prakash]

sir,

i use gridview where all date are retrieve from sql database,i use templete field and there is two textbox , i want when we change the value of textbox which is inside a gridview the value is changed when we click the save button...........
plese help me

page load event

 if (!IsPostBack)
        {
            string query = Request.QueryString["id"].ToString();
 
            SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["discussionForum"].ConnectionString);
            con.Open();
            SqlCommand cmd = new SqlCommand("SELECT  tblReguser.photo, tblReguser.username,tblComment.id, tblComment.timestamp,tblComment.description,tblComment.relevance FROM tblRegUser CROSS JOIN tblComment WHERE (tblComment.topic_id = @id and tblComment.user_id=tblReguser.id and tblComment.status='0')", con);
            cmd.Parameters.AddWithValue("@id", query);
            SqlCommand cmd1 = new SqlCommand("SELECT  tblReguser.photo, tblReguser.username,tblComment.id, tblComment.timestamp,tblComment.description,tblComment.relevance FROM tblRegUser CROSS JOIN tblComment WHERE (tblComment.topic_id = @id and tblComment.user_id=tblReguser.id and tblComment.status='1')", con);
            cmd1.Parameters.AddWithValue("@id", query);
            SqlDataAdapter adp = new SqlDataAdapter(cmd1);
            DataSet ds = new DataSet();
            adp.Fill(ds);
            GridView3.DataSource = ds;
            GridView3.DataBind();
            SqlDataReader rdr = cmd.ExecuteReader();
            GridView1.DataSource = rdr;
            GridView1.DataBind();
 
            con.Close();
        }

on button click

 
     protected void saveunblock_Click(object sender, EventArgs e)
    {
 
        Button lnk = sender as Button;
        string a = lnk.CommandArgument;
        foreach (GridViewRow row in GridView1.Rows)
        {
            if (row.RowType == DataControlRowType.DataRow)
            {
                TextBox t = (TextBox)row.FindControl("t2");
                CheckBox c = (CheckBox)row.FindControl("c2");
                string a1 = System.DateTime.Now.ToString();
                string myvalue = (string)Session["mykey"];
                SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["discussionForum"].ConnectionString);
                con.Open();
                if (c.Checked == true)
                {
                    SqlCommand cmd = new SqlCommand("update tblComment set status='0' where id=@id", con);
                    cmd.Parameters.AddWithValue("@id", a);
                    cmd.ExecuteNonQuery();
                    con.Close();
                    Response.Redirect("admintopic.aspx");
                }
            }
        }
    }