You can't perform recovery once the files are locked within the vault and the icon is hidden. Secondly, recovery is possible only with the application that hid the content. No other 3rd party apps can be used to recover content hidden by Secure Folder application.
Go to the application's page for your software to read more about the recovery procedure. As far as I know, you have to unlock those files or remove the hidden property by dialing the pin with the correct characters.
