<script>
function imgError(image) {
image.onerror = '';
image.src = 'product_images/unavail.png';
return true;
}
</script>



<!--<img src="<?php echo $pro_imagelink;?>" width="60" height="60"
  onError='imgError(this);'/>
    <img src="product_images/<?php echo $pro_image;?>" width="60"
 height="60" onerror="this.style.display='none'"/>-->

    <img src="product_images/<?php echo $pro_image;?>" width="60"
   height="60" onerror="this.src='<?php echo $pro_imagelink ?>'"/>