If you have deleted the files, then there is no possibility to return the S Notes files unless you have performed a backup of the internal or external storage. However, in many cases the data is automatically saved to the cloud. Go to Settings > Accounts > Google Account. Tap on the Google account attached to the phone and then perform a forced sync by tapping on Sync NOW. Make sure you are connected to Internet the whole time. If there is backup, you should see the Notes in the S Note application.