I have searched all over the Internet and I found the same things  I have already done.
I think I haven't made any mistake but my audio does not work.
Except the audio, all the other things work fine.
I am using jQuery.
Here is code snippet :
var buttonColors = ['red', 'green', 'yellow', 'blue'];
var gamePattern = [];
function nextSequence() {
  var randomNumber = Math.floor(Math.random() * 4);
  var randomChosenColor = buttonColors[randomNumber];
  gamePattern.push(randomChosenColor);
  $("#" + randomChosenColor).fadeOut(100).fadeIn(100).fadeOut(100).fadeIn(100);
  new Audio("sounds/" + randomChosenColor + ".mp3").play();
}
nextSequence();
html:
<!DOCTYPE html>
<html lang="en" dir="ltr">
<head>
  <meta charset="utf-8">
  <title>Simon</title>
  <link rel="stylesheet" href="style.css">
  <link href="https://fonts.googleapis.com/css?family=Press+Start+2P" rel="stylesheet">
</head>
<body>
  <h1 id="level-title">Press A Key to Start</h1>
  <div class="container">
    <div lass="row">
      <div type="button" id="green" class="btn green">
      </div>
      <div type="button" id="red" class="btn red">
      </div>
    </div>
    <div class="row">
      <div type="button" id="yellow" class="btn yellow">
      </div>
      <div type="button" id="blue" class="btn blue">
      </div>
    </div>
  </div>
  
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
  <script src="index.js"></script>
</body>
</html>
Here are folders: files used
 
     
    