Hi James Walsh,
Hope your day's fine. Let's try some options how to find your written Notes.
OneNote: Open OneNote in your computer or phone > Sign-in with the your Microsoft account you used in your old Notes app > Look for some notebook with titles like "Quick Notes", "Notes" or "Personal Notes" (these are typically imported from old notes). If it doesnt appear use the search bar in OneNote to search for keywords from your old notes.
Sticky Notes in Outlook: Open your Outlook on web browser >Notes > Sign in with your Microsoft Account you used > You may see your old Notes there as Sticky Notes. Your Notes can also be found in your Windows Sticky Notes (desktop) and OneNote Feed (desktop).
Not Signed-In MS Account Options (Notes stored locally): Open your file explorer and browse these file paths:
/Android/data/com.microsoft.office.notes/
/Android/data/com.microsoft.office.officehub/
/Android/data/com.microsoft.launcher/
These may contain cached note data like .sqlite or .xml files
Note: this is possible if you havent cleared storage.
Google Drive Backup if you use this, go to Settings>Google>Backup. Check if an older backup of the Office or Launcher app exists. Try installing old version to extract notes.
Samsung Cloud / Microsoft Launcher check this also if back-up is available depending on your phone.
Restore an Older App Version. if your notes were stored in the Office app (not synced), recovering your notes might be possible by reinstalling an older version of the Microsoft Office 365APK from a trusted mirror site > Turn-Off autoupdates > Check your notes if will reappear when you sign in.
I hope some of these options above find helpful.
Regards,
Jhun