How to enable paypal payment standard in magento 1.9.2.1
In magento 1.9.2.1 Paypal Payment Standard method not exist. If you want use paypal, you have to select Website Payments Standard (Includes Express Checkout). Here i have used small trick to reuse the old method.
Run the following query in your database and check in admin panel in payment method section
update core_config_data set value = '1' where path = 'payment/paypal_standard/active';