Invalid Form Key. Please refresh the page / Magento admin login

If you have this issue, the method below solve it be sure =)

I had the same problem and could fix it by setting the correct web/cookie/cookie_domain and web/cookie/cookie_path values in the table core_config_data.

Don't forget to clear all session and cookie data in your browser and the Magento session and cache files/data afterwards.

Good luck! 

Reset / Delete magento category / products by SQL for magento 1

Use query below. Works like a charm! =)

TRUNCATE TABLE `catalog_product_bundle_option`;
TRUNCATE TABLE `catalog_product_bundle_option_value`;
TRUNCATE TABLE `catalog_product_bundle_selection`;
TRUNCATE TABLE `catalog_product_entity_datetime`;
TRUNCATE TABLE `catalog_product_entity_decimal`;
TRUNCATE TABLE `catalog_product_entity_gallery`;
TRUNCATE TABLE `catalog_product_entity_int`;
TRUNCATE TABLE `catalog_product_entity_media_gallery`;
TRUNCATE TABLE `catalog_product_entity_media_gallery_value`;
TRUNCATE TABLE `catalog_product_entity_text`;
TRUNCATE TABLE `catalog_product_entity_tier_price`;
TRUNCATE TABLE `catalog_product_entity_varchar`;
TRUNCATE TABLE `catalog_product_link`;
TRUNCATE TABLE `catalog_product_link_attribute`;
TRUNCATE TABLE `catalog_product_link_attribute_decimal`;
TRUNCATE TABLE `catalog_product_link_attribute_int`;
TRUNCATE TABLE `catalog_product_link_attribute_varchar`;
TRUNCATE TABLE `catalog_product_link_type`;
TRUNCATE TABLE `catalog_product_option`;
TRUNCATE TABLE `catalog_product_option_price`;
TRUNCATE TABLE `catalog_product_option_title`;
TRUNCATE TABLE `catalog_product_option_type_price`;
TRUNCATE TABLE `catalog_product_option_type_title`;
TRUNCATE TABLE `catalog_product_option_type_value`;
TRUNCATE TABLE `catalog_product_super_attribute`;
TRUNCATE TABLE `catalog_product_super_attribute_label`;
TRUNCATE TABLE `catalog_product_super_attribute_pricing`;
TRUNCATE TABLE `catalog_product_super_link`;
TRUNCATE TABLE `catalog_product_enabled_index`;
TRUNCATE TABLE `catalog_product_website`;
TRUNCATE TABLE `catalog_product_entity`;
TRUNCATE TABLE `cataloginventory_stock`;
TRUNCATE TABLE `cataloginventory_stock_item`;
TRUNCATE TABLE `cataloginventory_stock_status`;
TRUNCATE TABLE `catalog_category_entity`;
TRUNCATE TABLE `catalog_category_entity_datetime`;
TRUNCATE TABLE `catalog_category_entity_decimal`;
TRUNCATE TABLE `catalog_category_entity_int`;
TRUNCATE TABLE `catalog_category_entity_text`;
TRUNCATE TABLE `catalog_category_entity_varchar`;
TRUNCATE TABLE `catalog_category_product`;
TRUNCATE TABLE `catalog_category_product_index`;
INSERT INTO `catalog_category_entity` (`entity_id`, `entity_type_id`, `attribute_set_id`, `parent_id`, `created_at`, `updated_at`, `path`, `position`, `level`, `children_count`) VALUES (1, 3, 0, 0, '2012-06-17 22:20:47', '2012-06-17 22:20:47', '1', 0, 0, 1), (2, 3, 3, 1, '2012-06-17 22:20:47', '2012-06-17 22:20:47', '1/2', 1, 1, 0);
INSERT INTO `catalog_category_entity_int` (`value_id`, `entity_type_id`, `attribute_id`, `store_id`, `entity_id`, `value`) VALUES (1, 3, 67, 0, 1, 1), (2, 3, 67, 1, 1, 1), (3, 3, 42, 0, 2, 1), (4, 3, 67, 0, 2, 1), (5, 3, 42, 1, 2, 1), (6, 3, 67, 1, 2, 1);
INSERT INTO `catalog_category_entity_varchar` (`value_id`, `entity_type_id`, `attribute_id`, `store_id`, `entity_id`, `value`) VALUES (1, 3, 41, 0, 1, 'Root Catalog'), (2, 3, 41, 1, 1, 'Root Catalog'), (3, 3, 43, 1, 1, 'root-catalog'), (4, 3, 41, 0, 2, 'Default Category'), (5, 3, 41, 1, 2, 'Default Category'), (6, 3, 49, 1, 2, 'PRODUCTS'), (7, 3, 43, 1, 2, 'default-category');
INSERT INTO `catalog_product_link_type` (`link_type_id`, `code`) VALUES (1, 'relation'), (3, 'super'), (4, 'up_sell'), (5, 'cross_sell');
INSERT INTO `catalog_product_link_attribute` (`product_link_attribute_id`, `link_type_id`, `product_link_attribute_code`, `data_type`) VALUES (1, 1, 'position', 'int'), (2, 3, 'position', 'int'), (3, 3, 'qty', 'decimal'), (4, 4, 'position', 'int'), (5, 5, 'position', 'int');
INSERT INTO `cataloginventory_stock` (`stock_id`, `stock_name`) VALUES (1, 'Default');