Web Forms :: Keep The Text In Textbox After Pageload?

i have the following two asp.net pages the default contains two textboxes and a button the second contains textbox with a button i saved the value of the textbox in the seconed page in session["1"] when click the button in this page it will redirect you to default in the default page on pageload events i have check the values of the session if one it will appear in textbox 1 if it tow it will appear in the textbox 2 but i lose the old values of the textbox when another get filled please tell me how to keep this values after it filled and the page load ,the session get the value to fill the other textbox her is the code: defualt protected void Page_Load(object sender, EventArgs e) { if (Session["1"]!=null) { switch (Session["1"].ToString()) { case "1": TextBox1.Text = Session["1"].ToString(); break; case "2": TextBox2.Text = Session["1"].ToString(); break; default: break; } } } protected void Button1_Click(object sender, EventArgs e) { Response.Redirect("WebForm1.aspx"); } webform1 protected void Button1_Click(object sender, EventArgs e) { Session["1"] = TextBox1.Text; Response.Redirect("Default.aspx"); }