oh yeah I made a slight mistake, try this
Code:

var music_handle;

string para_music;

function play_music(para_music,_loop,_volume)
{
  if(music_handle) { media_stop(music_handle); }
  
  if(!_loop) 
  { music_handle = media_play(para_music,null,_volume); }
  else 
  { music_handle = media_loop(para_music,null,_volume); }
}