Label Or Textbox Loses Value After Button Click

When I click the button the values of my label and texbox become null. Here's my code not working loses values when button is click

Code:

protected void Page_Load(object sender, EventArgs e)
{
string bid_id = Request.QueryString["bid_id"];
Label1.Visible = false;
if (!IsPostBack)

[Code] ....

Code:

protected void placeBid_texbox_Click(object sender, EventArgs e)
{
if (User.Identity.IsAuthenticated)
{
SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings["LocalSqlServer"].ConnectionString);

[Code] .....