Render a specific block

custom_block_render.php

<?php

//CUSTOM BLOCK RENDERING
function mytheme_block_render($module, $block_id) {
  $block = block_load($module, $block_id);
  $block_content = _block_render_blocks(array($block));
  $build = _block_get_renderable_array($block_content);
  $block_rendered = drupal_render($build);
  print $block_rendered;
}