Cross Postback

Note: Use Linkbutton or Hyperlink for postback dont use Response.Redirect()

In Default4:

<%@ PreviousPageType VirtualPath="~/Default3.aspx" %>

In Default3.cs

private string getstr;

  public string Getstr
  {
  get { return getstr; }
  set { getstr = value; }
  }

   
  protected void Page_Load(object sender, EventArgs e)
  {
  Getstr = "Jeyachandran";
  }

In Default4.cs

Response.Write(((TextBox)Page.PreviousPage.FindControl("TextBox1")).Text);
Response.Write(PreviousPage.Getstr);