reset.php

<?php
require 'app/Mage.php';
Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID); 

// Reset admin path.
$config = Mage::getSingleton('core/config');
$config->saveConfig('admin/url/custom_path', 'admin', 'default', 0);
$config->saveConfig('web/unsecure/base_url', '{{base_url}}', 'default', 0);
$config->saveConfig('web/secure/base_url', '{{base_url}}', 'default', 0);
$config->saveConfig('web/cookie/cookie_domain', '', 'default', 0);

// Create admin user (admin / admin123).
$user = Mage::getModel('admin/user');
$user->setData(array(
    'username' => 'admin',
    'firstname' => 'admin',
    'lastname' => 'admin',
    'email' => '[email protected]',
    'password' => 'admin123',
    'is_active' => 1,
));
$user->save();
$user->setRoleIds(array(1));
$user->setRoleUserId($user->getUserId());
$user->saveRelations();

Mage::app()->cleanCache();