using System.Runtime.InteropServices;    //命名空间

const uint WM_APPCOMMAND = 0x319;
const uint APPCOMMAND_VOLUME_UP = 0x0a;
const uint APPCOMMAND_VOLUME_DOWN = 0x09;
const uint APPCOMMAND_VOLUME_MUTE = 0x08;

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, uint wParam, uint lParam);

private void music_Click(object sender, EventArgs e)
{
SendMessage(this.Handle, WM_APPCOMMAND, 0x200eb0, APPCOMMAND_VOLUME_MUTE * 0x10000);
}