One of our forms has been deleted. It this due to an update from Jotform?

JotForm does not delete the user's forms without authorization. 

I would recommend you to search your form in the trash folder, you can restore it from there, this guide will help you doing so: https://www.jotform.com/help/134-How-to-Restore-Deleted-Forms 

If you cannot find the form, please share us the URL so we can search it on our end.