try this,

using System.Media;


public partial class finite : Form

    {

        public System.Windows.Forms.Button button1;

        public finite()

        {

            InitializeComponent();

        }

        SoundPlayer My_JukeBox = new
     SoundPlayer(@"C:\Users\katoto\Philcollins\true colours.mp3");

        public void btstart_Click(object sender, EventArgs e)

        {

           

            My_JukeBox.Play();

            

{