Images not showing after path specified in header.php

Use get_stylesheet_directory_uri() instead of get_stylesheet_directory().

<img src="https://wordpress.stackexchange.com/questions/239657/<?php echo get_stylesheet_directory_uri();?>/images/headerbg.jpg" ..../>

get_stylesheet_directory_uri() returns URI of the stylesheet directory where as get_stylesheet_directory() returns the path on the server to the stylesheet directory.