Lost note file, from “ON MY IPHONE” folder

After the last update of my i-Phone 7, (2 weeks ago - update 11.0.3. (15A432)), an important file of mine, kept in the application “Notes” in the folder “ON MY IPHONE” files, disappeared. The file is obviously not synchronized to i-Cloud.

I tried since then to find it, also with the help of the purchased for that reason program “EaseUS MobiSaver Proffesional 7.5” but I had no luck.

The file can’t be found, not even in the deleted.

Please advise if it can be restored somehow and why that may have happened.