All content in Notes disappeared. How to recover?

Hello DoDzung,

It appears you may have come across this page, though be sure to try out any and all suggestions that it will help to provide for that type of issue: If you're missing notes on your iPhone, iPad, or iPod touch - Apple Support

This will involve things like:

1. Checking account settings to ensure third-party accounts that the Notes may be synced with currently have the Notes option enabled

2. Check your Recently Deleted folder

3. Use Search to find your notes 

4. Manually search for your notes

Be sure to also try updating the device as the page mentions: Update your iPhone or iPad - Apple Support

It can also help to try restarting the device, and then check the Notes app afterwards to see if they've populated.

Ensure the device is also connected to a cellular data connection or a Wi-Fi network.

If they were being synced with iCloud, and nothing above helped, you may try reaching out to Apple Support for further guidance. This page can help start the support request: Apple Support

Cheers.

Thanks Eric, but it’s still notes is disappeared