Changes made on the forms were not saved.

great thanks! I've done all this and it works! That is it worked, but now it's all gone. In fact this is the second time I've lost it all. The first time I thought I may have forgotten to save it, so I did it all again and even had paypal all set up etc, but now all the modifications are gone again even though I took many pains to make sure it was saved. What happened? I'm sure I'm missing something.

I found my previous form in revision history, but the odd thing is it shows that I deleted all those updates I made -- which I didn't do (intentionally anyway).

I'm sorry for the inconvenience this have caused you. 

I'm not particularly sure what happened, as you have said, you made sure that everything was saved properly after making some changes on your form. And there are no known issue when it comes to saving forms.

I would suggest you make use of the "Revert to this version" button of the Revision History feature that is available on each form. 

To access it, 

Go to your MyForms page. 

Then, 

From there, you can revert back to where your form is working fine. 

Let us know if you need any further assistance. Thank you.