I've just tried to revert my form to a previous version and now Jotform has lost the whole form!

Help, Jotform has lost my form! 

I've just tried to revert my form to a previous version and now Jotform has lost the whole form!

I can see the for at https://www.jotform.com/61825276346360 

I would suggest you to clear the form cache and the browser cache and check again.

Browser cache http://www.refreshyourcache.com/en/home/
Form cache https://www.jotform.com/help/229-How-to-Clear-Your-Form-Cache

If the issue continues, you can restore back the form using the Revision history https://www.jotform.com/help/294-How-to-View-Form-Revision-History

Hope this helps