How to Get value from row of the grid view into textbox of parent page from Child page

<asp:button id="Button1" runat="server" text="Button" commandname="Select" xmlns:asp="#unknown" />

if (e.CommandName == "Select")
  {
      ImageButton img = (ImageButton)e.CommandSource as ImageButton;
      GridViewRow row = img.NamingContainer as GridViewRow;

      Label name = (Label)row.FindControl("label1");
      Session["Value"] = name.Text;


      Response.Redirect("page2.aspx");
  }

TextBox1.Text = Session["Value"].ToString();

Try this...:

Aspx page :

         <asp:TemplateField HeaderText="Action">
                    <ItemTemplate>
                        <asp:LinkButton ID="lnkSelect" runat="server" Text="Select" OnClick="lnklnkSelect_Click" CommandArgument='<%# Eval("UrValue") %>'></asp:LinkButton>
                    </ItemTemplate>
        </asp:TemplateField> 

CS :

protected void lnklnkSelect_Click(object sender, EventArgs e)
    {
        con.Open();
        string lb1Value = ((LinkButton) sender).CommandArgument.ToString();
        Response.Redirect("UrPage.aspx?+lb1Value");
    }

Then in your parent page, get that value like :

if(Request.QueryString["lb1Value"] != null)
{
   TextBox.Text=Request.QueryString["lb1Value"];
}