Q:

How to Sort list

I trying to sort this list by pressing the sort button? im having trouble with the coding part!

A:

From the top of my head (I can't test it myself right now), I would do this:
private void btnSort_Click(object sender, RoutedEventArgs e)
{
    List<string> list = lstbxResults.Cast<string>().OrderBy(p=>p).ToList();

    lstbxResults.Clear();
    foreach(var item in list)
        lstbxResults.Items.Add(item);
}

edit: I put a Cast to obtain an IEnumerable

