[Solved] Unable to get TextBox inside GridView values modified client side using jQuery on Server Side in ASP.Net

hello all, i have a grid as 

<asp:GridView ID="dgv_passengerdetails" runat="server" AutoGenerateColumns="False"
                                         CssClass="pasdetailsgrid" BorderStyle="None">
                                        <Columns>
                                            <asp:BoundField HeaderText="Seat No" DataField="seatno">
                                                <ItemStyle HorizontalAlign="Center" />
                                            </asp:BoundField>
                                                                                       <asp:TemplateField HeaderText="Name">
                                                <ItemTemplate>
                                                    <asp:TextBox ID="txtpname" ViewStateMode="Enabled" runat="server" Width="300" CssClass="buslookuptxt" onKeyPress="ValidateAlpha();"></asp:TextBox>
                                                </ItemTemplate>
                                                <ItemStyle HorizontalAlign="Center" />
                                            </asp:TemplateField>
                                            <asp:TemplateField HeaderText="Age">
                                                <ItemTemplate>
                                                    <asp:TextBox ID="txtpage" ViewStateMode="Enabled" runat="server" Width="50" CssClass="buslookuptxt" onkeypress="return onlyNumbers(this);"></asp:TextBox>
                                                </ItemTemplate>
                                                <ItemStyle HorizontalAlign="Center" />
                                            </asp:TemplateField>
                                        </Columns>
                                        <HeaderStyle BackColor="#CCCCCC"></HeaderStyle>
                                    </asp:GridView>

i am binding 1st column bound field using client side code(using json,jquery,webservice) when i fill the information in textbox and click the button at first click the values are null for example if i write the code on button click as

foreach (GridViewRow gr in dgv_passengerdetails.Rows)
            {
                string gs = ((TextBox) gr.Cells[2].FindControl("txtpname")).Text;
            }

the string gs=null, if i click the button again then gs takes the value from textbox. how i can solve the issue