You have lost previously obtained coins and/or upgrades.
First, make sure you have updated to the latest version of Nuts! available on the App Store.
To save and load backups, your device must be updated to iOS 5.0 or later. Check that your internet connection is working and make sure iCloud Documents & Data is set to 'On' in your device settings. With iCloud enabled, your progress in Nuts! will be automatically saved and can be restored to any of your supported devices.
Tap the gear icon on the main menu and then tap Load Backup to search for any online backups you may have. If any backup games are found, you can select the desired backup to load it from iCloud.
If you have lost your game progress and could not successfully restore a backup of your game, please email at firstname.lastname@example.org and we will be able to assist you.