WPF Textbox.Text, when Checkbox.IsEnabled with Button

i am using WPF and want to create a "Search"-Window (Window2), related to Window1.

The "Search"-Window has to each checkbox at least one textbox and at the end a "Search"-Button. I don´t want to use

namespace PokemonManager{

/// <summary>
/// Interaktionslogik für suchen.xaml
/// </summary>
public partial class suchen : Window
{

    //Werte uebergeben
    //Name
    private string text_name = "";
    public string textName
    {
        get { return text_name; }
    }

    privat void search_click(object sender, RoutedEventArgs e){
        if(check_name.IsChecked == true){
           //do this
        }

for each checkbox, so I want to create a switch-case for each checkbox to say at the end "This checkboxes are checked, so just search with the Textbox.Text related to the checkboxes.

I´ve tried it with this lines

//Suchen-Button
    public void search_Click(object sender, RoutedEventArgs e)
    {

        CheckBox sender_ch = sender as CheckBox;

        if (sender_ch != null)
        {
            switch (sender_ch.Tag)
            {
                case "tag_name":
                    if (search_name.IsChecked == true)
                    {
                        MessageBox.Show("Hi");
                        text_name = txt_name.Text;
                    }
                    break;
             }
        }
}

I´ve tried it with this lines in

private void chechbox_checked(object sender, RoutedEventArgs e)

too, but there is the problem, that the checkbox take the textbox-Value before I entered a text.

Can I get anyhow the text after I checked a checkbox with a switch-case?

Sry, if I didn´t formated the text in the right way. I hope you can help me and you understand my question!