<?php
 
 define('MAGENTO', realpath(dirname(__FILE__)));
 require_once MAGENTO . '/app/Mage.php';
 umask(0);
 Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID); 
 
 $file = fopen(MAGENTO . "/var/import/categoriesToEnable.csv", 'r');
 
 while (($line = fgetcsv($file)) !== FALSE) {
 $cats = explode(",",$line[1]);
 foreach ($cats as $cat) {
 $newcats[$cat] = true;
 }
 } 
 
 // Activate the categories it is in 
 foreach ($newcats as $cat=>$value) {
 
 if ($value && !empty($cat)) {
 
 try {
 
 $_category = Mage::getModel('catalog/category')->load($cat);
 
 if ($_category->getIsActive() === "0" || !$_category->getIsActive()) {
 $_category->setIsActive(1);
 $_category->save();
 echo "<br />Enabled ".$_category->getName();
 unset($_category);
 }
 
 } catch(Exception $e) {
 echo " Caught Cat Insert exception: ", $e->getMessage();
 }
 }
 
 }
 
?>

<?
 
 define('MAGENTO', realpath(dirname(__FILE__)));
 require_once MAGENTO . '/app/Mage.php';
 umask(0);
 Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID); 
 
 $file = fopen(MAGENTO . "/var/import/categoriesToEnable.csv", 'r');
 
 while (($line = fgetcsv($file)) !== FALSE) {
 $cats = explode(",",$line[1]);
 foreach ($cats as $cat) {
 $newcats[$cat] = true;
 }
 } 
 
 // Activate the categories it is in 
 foreach ($newcats as $cat=>$value) {
 
 if ($value && !empty($cat)) {
 
 try {
 
 $_category = Mage::getModel('catalog/category')->load($cat);
 
 if ($_category->getIsActive() === "0" || !$_category->getIsActive()) {
 $_category->setIsActive(1);
 $_category->save();
 echo "<br />Enabled ".$_category->getName();
 unset($_category);
 }
 
 } catch(Exception $e) {
 echo " Caught Cat Insert exception: ", $e->getMessage();
 }
 }
 
 }
 
?>

http://www.sonassi.com/knowledge-base/magento-knowledge-base/quick-script-to-mass-enable-categories-in-magento/

Create a CSV with a maximum of 1 column, with just the Magento category ID.

Mass enable categories

magento

PHP