ต้องการนำข้อมูลใน textbox ที่กรอกใน gridview ออกมาใช้งาน

 <Columns>
   <asp:TemplateField HeaderText="Recorded Date">
                        <ItemTemplate>
                            <asp:Label ID="lblrecorddate" runat="server" Text='<%# Bind("recorddate") %>'></asp:Label>
                        </ItemTemplate>
                        <ItemStyle HorizontalAlign="Center" />
                    </asp:TemplateField>
                  <asp:TemplateField HeaderText="Recorded by">
                        <ItemTemplate>
                            <asp:Label ID="lblrecordby" runat="server" Text='<%# Bind("recordby") %>'></asp:Label>
                        </ItemTemplate>
                        <ItemStyle HorizontalAlign="Center" />
                    </asp:TemplateField>
                   
                    <asp:TemplateField HeaderText="Responsible">
                        <ItemTemplate>
                            <asp:TextBox ID="txtresponse" runat="server" Height="40px" Width="200px" 
                                TextMode="MultiLine" Text='<%# (Eval("status"))== "Pending" ? "":Eval("responsetext")%>'></asp:TextBox>
                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:BoundField HeaderText="Responsible by" DataField ="responseby"/>
                   
                      <asp:TemplateField HeaderText="Responsible Date">
                        <ItemTemplate>
                            <asp:Label ID="lblresponsedate" runat="server" Text='<%# Bind("responsedate") %>'></asp:Label>
                        </ItemTemplate>
                        <ItemStyle HorizontalAlign="Center" />
                    </asp:TemplateField>
                    <asp:TemplateField HeaderText="Status">
                        <ItemTemplate>
                            <asp:DropDownList ID="ddlactionstatus" runat="server" text='<%# Bind("status") %>' >
                                <asp:ListItem>Pending</asp:ListItem>
                                <asp:ListItem>Inprocess</asp:ListItem>
                                <asp:ListItem>Complete</asp:ListItem>
                            </asp:DropDownList>
                        </ItemTemplate>
                    </asp:TemplateField>
                </Columns>

 GridView1.DataSource = DT;
                    GridView1.DataBind();
                    DT.Dispose();

                    for (int i = 0; i <= GridView1.Rows.Count - 1; i++)
                    {
                       TextBox responsetext = (TextBox)GridView1.Rows[i].FindControl("txtresponse");

                        Label lblrecorddate = (Label)GridView1.Rows[i].FindControl("lblrecorddate");
                        Label lblresponsedate = (Label)GridView1.Rows[i].FindControl("lblresponsedate");

                        lblrecorddate.Text = Convert.ToDateTime(lblrecorddate.Text).ToString("dd/MM/yyyy HH:mm");
                        if (lblresponsedate.Text != "")
                        {
                            lblresponsedate.Text = Convert.ToDateTime(lblresponsedate.Text).ToString("dd/MM/yyyy HH:mm");
                        }