Restoring your Notes on your iPhone is a relatively simple process. Firstly, ensure that your iPhone's operating system is up-to-date. Then, open the Notes app and navigate to the folder where the lost notes were located. Tap the "Recently Deleted" folder and check if the notes are present there. If yes, select the notes to restore and tap "Restore". If the notes aren't in the "Recently Deleted" folder, you can try restoring them from an iCloud or iTunes backup. To do so, connect your iPhone to your computer, open iTunes, select your device, and click "Restore Backup". Alternatively, you can also restore a backup through iCloud by going to "Settings" > "General" > "Reset" > "Erase all contents and settings" and then following the prompts to restore your data from an iCloud backup. Remember to back up your iPhone regularly to avoid losing any important data in the future.