Music Background is not working in Scorm Cloud

It might just be the modern browser security settings getting in your way. You might need to add an "enter course" slide or a "play button"; anything that requires the user to interact with the browser.  Change your javascript to run when that interaction happens rather than at timeline start. Note that this is a recent browser requirement and not a SL limitation. 
See if that solves your issue.

See my suggestions below

1. O̶n̶ ̶F̶i̶l̶e̶ ̶P̶u̶b̶l̶i̶s̶h̶ ̶O̶u̶t̶p̶u̶t̶ ̶s̶t̶o̶r̶y̶_̶h̶t̶m̶l̶5̶:̶ ̶a̶d̶d̶i̶n̶g̶ ̶t̶h̶i̶s̶ ̶c̶o̶d̶e̶ ̶ ̶ ̶<̶a̶u̶d̶i̶o̶ ̶s̶r̶c̶=̶"̶y̶o̶u̶r̶ ̶a̶u̶d̶i̶o̶ ̶f̶i̶l̶e̶ ̶n̶a̶m̶e̶.̶m̶p̶3̶"̶ ̶i̶d̶=̶"̶b̶g̶S̶o̶n̶g̶"̶ ̶p̶r̶e̶l̶o̶a̶d̶=̶"̶a̶u̶t̶o̶"̶ ̶a̶u̶t̶o̶p̶l̶a̶y̶ ̶l̶o̶o̶p̶>̶<̶/̶a̶u̶d̶i̶o̶>̶
Don't manually add the code... let Javascript add it for you.  Add a trigger to execute JavaScript at Timeline start and use the following code:

//create a function to add the music elements dynamically into the head of the html document
function add_line() {
var line = document.createElement("audio");
var head=document.getElementsByTagName('body')[0];
line.type = "audio/mp3";
line.src="";
line.id="bgSong" ;
line.autoplay = true;
line.loop = true;
head.appendChild(line);
}

//run the function only if the added html lines have not already been added
if(document.getElementById('bgSong')==null){
add_line();
var audio = document.getElementById('bgSong');
audio.volume = 0.5;
}

2. On Storyline Trigger--> Execute javascript when time line start:
var audio = document.getElementById('bgSong');
audio.src="1.mp3"; // be sure you are including the FULL URL or RELATIVE path to where the music is located

audio.load();
audio.play();

Hi all

When i close the course and resume where i left the background music not playing. Please help me in this.