Although you can even recover deleted notes by using third-party app like MiniTool Mobile Recovery. There are some methods to best keep your notes safe , it's really a big trouble if your notes are lost.
Here are some tips for you:
- Frequently update your iCloud backup and iTunes backup.
- Allow your Notes APP to synchronize with other applications, for instance, email. This offers you another path to store your important notes.
- Make sure that you have made an iTunes or iCloud backup before upgrading iOS version or restoring your iOS devices to factory settings.