I found it myself. Uploaded file details are stored in table 'mdl_files'. I was able to show the file using below code.
$fs = get_file_storage();
$file = $fs->get_file_by_hash(sha1($filepath));
send_stored_file($file, 0, 0);
where $filepath is dynamically generated as below"/$context->id/mod_lesson/mediafile/0".$lesson->mediafile