Most raising issue with html website. When you insert images into a page that can not be viewed because there is no original image. If the picture does not show, then the look of your site deteriorates. So it is very important that you fix it. Very simple way to you can fix it.
<img src="SomeImage.jpg" onerror="this.onerror=null; this.src='Default.jpg'">
I think this is simplest way to solve this problem is.