I'm a high school teacher. I have taught thousands of students over the years. I remember only some of them by name and/or face (honestly rarely by face because physical appearance changes so much), and I've only personally kept in contact with a handful.

I get stopped constantly when I go out shopping, etc. by former students, often 20-30 years later. They always remind me who they were, what class I taught them in, etc. They humorously apologize for whatever grief they gave me when I taught them. LOL. We may chat for a minute and then we go on our way. That's my normal. It's nice they remember me. I don't feel guilty for not remembering them; too many students to possibly keep in my memory.

It would be really odd for a former student I haven't kept up with for 20 years to suddenly start asking for contact. It just doesn't happen often. When it does, it is because that former student now has become a teacher and we've crossed paths professionally or something along that line.

The former students I have kept up with are people I kept up with from the moment they graduated -- several of them are now teachers and actually teaching on my campus which is really cool. A couple I taught for several years so they were more imprinted in my memory. A few I've helped with letters of recommendations, etc., but we don't really keep up with each other - we may just occasionally cross paths on facebook or something.

I would guess your former teacher doesn't remember you. She might recall you somewhat by name, but appearance changes so much that she won't recognize you by face. Even if she recognizes your name, it doesn't really mean she remembers you - just that the name rings a bell somewhere in the annals of memory.

Let this one go. It isn't personal; it's just the reality of thousands of contacts with students and 20 years of distance.