textchange for dynamic generated row of textbox

int rowindex = 0;
            // if (ViewState["CurrentTable"] != null)
            // {
            // DataTable dt =new DataTable("tblAcHedas");// ((DataTable)ViewState["CurrentTable"]);
            // DataRow dr = null;
            // if (dt.Rows.Count > 0)
            // {

            // for (int i = 1; i <= dt.Rows.Count; i++)
            // {

            TextBox box1 = (TextBox)GridView1.Rows[rowindex].Cells[1].FindControl("TxT_AcC");
            TextBox box2 = (TextBox)GridView1.Rows[rowindex].Cells[3].FindControl("TxtDesc");

            //dr = dt.NewRow();
            // dt.Rows[i-1]["Column1"] = box1.Text;
            // dt.Rows[i-1]["Column3"] = box2.Text;

            //rowindex++;
            DataTable dt = new DataTable("tblAcHedas");// ((DataTable)ViewState["tblAcHedas"]);

            //DataRow dr = null;
            SqlConnection connection = new SqlConnection("Data Source=NABIN;Initial Catalog=AcDb;User ID=sa;Password=sic");
            connection.Open();
            SqlCommand sqlCmd = new SqlCommand("SELECT * FROM tblAcHedas WHERE AccCode= @AccCode", connection);
            SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd);
            sqlCmd.Parameters.AddWithValue("@AccCode", box1.Text);
            sqlDa.Fill(dt);

            // box2.Text = dt.Rows[rowindex]["AccName"].ToString(); //Where ColumnName is the Field from the DB that you want to display

            if (dt.Rows.Count > 0)
            {
                box2.Text = dt.Rows[0]["AccName"].ToString();
                ViewState["tblAcHeads"] = dt;

                // EnableViewState = true;

            }
            connection.Close();