how to create twitter card without plugin ?

Hi @tanmaybaijal Please paste this following code in your header.php file just before to the </head> tag.

<?php
if(is_single() || is_page()) {
  $twitter_url    = get_permalink();
 $twitter_title  = get_the_title();
 $twitter_desc   = get_the_excerpt();
   $twitter_thumbs = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), full );
    $twitter_thumb  = $twitter_thumbs[0];
      if(!$twitter_thumb) {
      $twitter_thumb = 'https://www.gravatar.com/avatar/8eb9ee80d39f13cbbad56da88ef3a6ee?rating=PG&size=75';
    }
  $twitter_name   = str_replace('@', '', get_the_author_meta('twitter'));
?>
<meta name="twitter:card" value="summary" />
<meta name="twitter:url" value="<?php echo $twitter_url; ?>" />
<meta name="twitter:title" value="<?php echo $twitter_title; ?>" />
<meta name="twitter:description" value="<?php echo $twitter_desc; ?>" />
<meta name="twitter:image" value="<?php echo $twitter_thumb; ?>" />
<meta name="twitter:site" value="TWITTER HANDLE" />
<?
  if($twitter_name) {
?>
<meta name="twitter:creator" value="@<?php echo $twitter_name; ?>" />
<?
  }
}
?>

Also you can use wp_head hook to insert this code into the head tag using functions.php file

not working this code

Did you change the Twitter Handle value with your twitter handle?

No