C#

public partial class Form1 : Form
 {

     TextBox textbox;
     public Form1()
     {
         InitializeComponent();
         listBox1.SelectedIndexChanged += listBox1_SelectedIndexChanged;
         textbox = new TextBox { Dock = DockStyle.Top };
         listBox1.SelectionMode = SelectionMode.MultiExtended;
     }

     private void Form1_Load(object sender, EventArgs e)
     {
       List<string> prova =  GetListOfFiles(@"D:\\Torrent\\Depeche Mode - Sounds Of The Universe (2009)\\");

         listBox1.DataSource = prova;
         listBox1.DisplayMember = "prova";
         player1.settings.setMode("Shuffle", true);
         player1.Ctlcontrols.play();

     }

     private List<string> GetListOfFiles(string Folder)
     {
         DirectoryInfo dir = new DirectoryInfo(Folder);
         FileInfo[] files = dir.GetFiles("*.mp3", SearchOption.AllDirectories);
         List<string> str = new List<string>();
         foreach (FileInfo file in files)
         {
             str.Add(file.FullName);

         }
         return str;
     }

      private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
     {
         Text = Convert.ToString(listBox1.SelectedItem);
         player1.URL = Convert.ToString(listBox1.SelectedItem);
     }

     private void textBox1_KeyDown(object sender, KeyEventArgs e)
     {
         if (e.KeyCode == Keys.Return)
         {
             string searchFor = textBox1.Text;
             List<string> strings = (List<string>)listBox1.DataSource;
             if (multi.Checked)
             {
                 for (int i = 0; i < strings.Count; i++)
                 {
                     listBox1.SetSelected(i, strings[i].Contains(searchFor));
                 }
             }
             else
             {
                 listBox1.ClearSelected();
                 listBox1.SelectedIndex = strings.FindIndex(
                     s => s.Contains(searchFor));
             }
         }
     }


 }