Good evening Ellen and welcome back!
Thank you for reaching out to us and for the system information.
We are sorry to hear that your plugin stopped working!
I would love to help you with this topic.
From what I am seeing on this site, the following message is returned on the checkout page: “Sorry, your session has expired. Return to homepage”.
This looks like a conflict between WooCommerce and another plugin.
After a backup, you might want switching temporarily to a maintenance mode / coming soon page to do the following:
- Deactivating and reactivating our plugins as well as WooCommerce related plugins
- Re-saving your permalinks (without changing them)
- Temporarily switch back to a default WordPress theme such as twenty-fifteen
- Temporarily deactivate the following plugins: Yoast SEO and Revolution Slider
Let me know how that goes.
Best regards,
Geoff B.