Thank you for posting to our forums!
I'm sorry to hear you have run into troubles with your BigCommerce Canvas store. I would recommend following the steps in this article in order to re-connect the store: How do I reconnect my BigCommerce Canvas (Single-Click install) store?
If that doesn't do the trick, you could log into ShippingEasy directly and integrate your BigCommerce store there. We did not prompt you for a password when creating your ShippingEasy account from within Bigcommerce but gaining access is easy - just go to the ShippingEasy application in a browser. Type in your email address and then click the link for Forgot your password. We will send you an email so that you can reset your password. Then you can login from the ShippingEasy web site.
Once you are logged in there, follow these steps for integrating your BigCommerce store directly into ShippingEasy:
If you have further questions, please let me know in the comments. Thanks!