I've lost all my notes
My phone was repaired and when I got it back there was nothing in notes
iPhone 7, iOS 15
Question marked as
You must always backup your device before sending it for repair - as the repair process will erase all locally stored data.
If you have enabled Notes in iCloud, your Notes will still be accessible after your iPhone has been signed-in to your AppleID account using your AppleID:
Settings > [Your Name / AppleID] > iCloud > Notes - set to ON
Otherwise, if not using iCloud, your Notes (and other files) may be present in your iCloud or iTunes backup if you have one - and can be restored to your iPad:
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support