Disappearing notes in Apple Notes app

I have very important notes in the Note application that I cannot do without. They disappeared once and I got them back through someone who posted them on a social networking site. Now I tried the method and did not benefit from it. This problem can cause very bad things and harm and cause problems. There may be elderly people who register in it and they disappear. Please, Apple Company, review the topic. I have very, very important things that I cannot do without. Help me. I will be grateful to you and thank you for helping me.

[Re-Titled by Moderator]