Hi
We'd like to help. Did you already follow all of the steps under "If you're missing notes on your iPhone, iPad, or iPod touch"? If not, we recommend trying every suggested step there. You mentioned that it was "most" of your notes. If some are there, what is the difference between the ones you see and the missing notes? Were they associated to an email account? If so, have you checked the Notes file in the email account? Did you have iCloud enabled for Notes? If so, do you see it turned on when you go to Settings > Tap your name > iCloud?
Please provide as much detail as possible to help us isolate the issue and try to find a resolution.
Cheers!