Q: ipod iOS 6.1.6

First if the deleted notes are i a backup, restore from backup

o restore from backup see:

Restore your device from an iCloud or iTunes backup - Apple Support

https://support.apple.com/en-us/HT204184

If you restore from iCloud backup the apps will be automatically downloaded. If you restore from iTunes backup the apps and music have to be in the iTunes library since synced media like apps and music are not included in the backup of the iOS device that iTunes makes.

You can redownload most iTunes purchases by:

Downloading past purchases from the App Store, iBookstore, and iTunes Store   

https://support.apple.com/en-us/HT201272

If not backup then maybe:

http://www.reviewstown.com/data-recovery-for-ios.html

http://www.video-converter-mac.org/ipad-recovery/