We have discontinued the free plan for version 3.x of Backendless on November 1st, 2017. The API calls for all apps which were on the free plan at that time were blocked. Two months later the apps which were not upgraded to a paid plan in version 3 were removed from the system.
If you would like us to restore your app, there is a $50/app administration fee. Once an app is restored, it needs to be switched to a paid plan since the free plan is not available there anymore. If you would like to proceed, use the link below to pay the fee. Once a payment is processed, please let us know application ID and we will work on restoring the app: