在开始加入
using System.Runtime.InteropServices;

在类中加入
[DllImport("winmm.dll", EntryPoint="mciSendString",CharSet=CharSet.Auto)]
public static extern int mciSendString (string lpstrCommand,string lpstrReturnstring ,int uReturnLength,int hwndCallback);

加入两个按钮
private void opencdrom_Click(object sender, System.EventArgs e)
{
　　long lngReturn = mciSendString("set CDAudio door open", null, 127, 0);
}

private void closecdrom_Click(object sender, System.EventArgs e)
{
　　long lngReturn = mciSendString("set CDAudio door closed", null, 127, 0);
}