Check this sample
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>Untitled Page</title>
</head>
<body style="font-family: Arial; font-size: 10pt">
<form id="form1" runat="server">
UserName: <asp:TextBox ID="txtUserName" runat="server"></asp:TextBox><br />
Password: <asp:TextBox ID="txtPassword" TextMode = "Password" runat="server"></asp:TextBox><br />
Remember me: <asp:CheckBox ID="chkRemember" runat="server" /><br />
<asp:Button ID="btnLogin" runat="server" Text = "Login" OnClick="Login_Click" />
</form>
</body>
</html>
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
if (Request.Cookies["UserName"] != null && Request.Cookies["Password"] != null)
{
txtUserName.Text = Request.Cookies["UserName"].Value;
txtPassword.Attributes["value"] = Request.Cookies["Password"].Value;
}
}
}
protected void Login_Click(object sender, EventArgs e)
{
if (chkRemember.Checked)
{
Response.Cookies["UserName"].Value = txtUserName.Text.Trim();
Response.Cookies["UserName"].Expires = DateTime.Now.AddDays(30);
Response.Cookies["Password"].Value = txtPassword.Text.Trim();
Response.Cookies["Password"].Expires = DateTime.Now.AddDays(30);
}
}