Hovik,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
@import url('https://fonts.googleapis.com/css?family=Old%20Standard%20TT&display=swap');
ul.timer {
list-style: none;
display: flex;
font-size: 3em;
margin: 20px;
padding: 0;
justify-content: center;
font: 400 2.4em / 23px "Old Standard TT", sans-serif;
}
</style>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script>
jQuery(document).ready(function($) {
let timer_start, timer_end, distance, hour, minut, second, now;
now = Date.now();
timer_start = new Date("2021-01-13 12:32:46").getTime();
timer_end = new Date("2021-01-15 12:32:46").getTime();
distance = (timer_end - now) / 1000 ;
if (now < timer_start || now > timer_end) return;
let x = setInterval(() => {
distance--
hour = Math.floor(distance / (60 * 60));
minut = Math.floor(distance / 60 % 60);
second = Math.floor(distance % 60)
$('.timer').html('<li>' + hour + ':</li><li>' + minut.toString().padStart(2, "0") + ':</li><li>' + second.toString().padStart(2, "0") + '</li>')
}, 1000);
if (distance < 0) clearInterval(x);
});
</script>
</head>
<body>
<ul class="timer" id="timer"></ul>
</body>
</html>