What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Your form, http://www.jotform.us/form/51196314556154, was created using a guest account. And you can only access it using the same browser you have used when you created it as it relies in cookies. If your cookies have been cleared, you can't logged into it anymore.
I suggest you clone your old form into your new account. A guide in cloning forms can be found here: How to clone an existing form from a URL.
Do let us know if you need further assistance.