Go back to top result of listbox?

I have a listbox that, when a button is pressed, the next item in the index is selected. Once the final result is reached, that one result is continuously selected. How would I get my program to go back to the top and select the first item after reaching the final result of the listbox?

private void NextBtn_Click(object sender, EventArgs e)
        {
            NextBtn.Enabled = false;
            if (Playlist.SelectedIndex<Playlist.Items.Count - 1)
            {
                Playlist.SelectedIndex = Playlist.SelectedIndex + 1;
            }     
        }