Good evening Rebecca and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
We are sorry to hear about the ticket dropdown being gone!
I would love to help you with this topic.
As a first troubleshooting step, could you please provide us with your system information in a private reply ? (following the instructions found in the link)
Secondly, would you mind heading over to the plugins page and make sure that your Event Tickets Plus plugin is activated (sometimes it deactivates after an update).
Let me know how that goes.
Best regards,
Geoff B.