Unable to get back textbox enable property set to true once it is set to false on textchanged event?

Question

I have a web form in which I am trying to set the textbox control property to false on textchanged event. I have multiple textbox's and I have taken these into a panel. Now I am checking a condition within the text changed event of the textbox. If the condition matches then there will be no change but if not then I will set the enable property of the textbox's within panel control to false. This is what I am doing-

<asp:TextBox ID="TextBox1" runat="server" Width="150px" AutoPostBack="True" 
        ontextchanged="TextBox1_TextChanged"></asp:TextBox>
<asp:Panel ID="Panel1" runat="server">
            <asp:TextBox ID="txt1" runat="server"></asp:TextBox>
            <asp:TextBox ID="txt2" runat="server"></asp:TextBox>
            <asp:TextBox ID="txt3" runat="server"></asp:TextBox>
</asp:Panel>

my cs code-

protected void TextBox1_TextChanged(object sender, EventArgs e)
    {
        SqlConnection cons1 = new SqlConnection(ConfigurationManager.ConnectionStrings["constr"].ConnectionString);
        cons1.Open();
        SqlCommand scmd1 = new SqlCommand("select name from tbl_names where name='"+TextBox1.Text+"'", cons1);
        SqlDataReader sdr1 = scmd1.ExecuteReader();
        if (sdr1.HasRows)
        {
            while (sdr1.Read())
            {
                Panel1.Visible = true;
                Control ctrl = new Control();
                foreach (Control c in ctrl.Controls)
                {
                    if (c is TextBox && c.ID.StartsWith("txt"))
                        ((TextBox)c).ReadOnly = false;
                }
            }
        }
        else
        {
            Panel1.Visible = true;
            Control ctrl1 = new Control();
            foreach (Control c in ctrl1.Controls)
            {
                if (c is TextBox && c.ID.StartsWith("txt"))
                    ((TextBox)c).ReadOnly = true;
            }
        }
        cons1.Close();
    }

Please guide me why this is not working?

Answer 1

I think your

Control ctrl = new Control();
foreach (Control c in ctrl.Controls)

Should be

foreach (Control c in Panel1.Controls)

Also, you're talking about Enabled property but you do not use it in your code. But from what you're saying, I don't think there will be textchanged events thrown if the textbox is be disabled.