Click on the "Details" button on the environment you want to start (Test / Acceptance / Production)
Click 'Start Application if the application is not running, or 'Restart Application' if the app is already running.
Paul Ketelaars - Deprecated
Probably your environment was cleared because the back-up was created using an older version of your application. Now the database is restored, you can deploy the desired version (for example the old version or the latest) to the acceptance environment: