[Plugin: Woo Commerce] Order confirmation emails not sending

Currently when a customer orders a product they no longer receive a confirmation email. All other emails including ones going to my own email for order notification is working. All settings in the control panel seem to be working and those email alerts are turned on. I’m running Woocommerce version 2.2.1.. I’ve tried to upgrade to 2.4 but several features in the backend stopped working..

Where can I start on touble shooting this issue