My form reverted back to the original

and unfortunately enough, all the work I did on this form - which I had cloned - reverted back to the original. I lost 2 hours of work. Is there any reason that happened? 

Sorry from inconvenience this may caused you. You can revert your form to previous version. Inside of this guide you can find how to do it:

https://www.jotform.com/help/294-How-to-view-form-revision-history 

If you had your form builder opened in multiple tabs when you edited your form it is possible that wrong version of your form was save. To prevent that wrong version of your form is saved, please to not open Form Builder in multiple tabs or browsers.

Hope this will help. Let us know if you need further assistance. 

had NO idea of that feature!!! Fantastic - you saved me, thanks!!!!

You're welcome. 

Feel free to contact us if you have any other questions.