[XK]

Just use

pawn Код:

PlayAudioStreamForPlayer(playerid, link);

You can get the link of the song and paste it there,i mean at PlayAudioStream...
and when the player presses on R,it shows him a dialog with song names,when he chooses the song it plays a song from the link for the song
and make it when he presses on R again it stops the music if you want by using:

pawn Код:

StopAudioStreamForPlayer(playerid);