I want to send a message to someone who doesn't know me, but I don't want to be rejected.

You: Excuse me, are you XXX? (Random name) I changed my mobile phone, remember to keep in touch.

Then he's sure to say you're mistaken,

You: Then who are you?

Then he will ask who you are, and you will keep talking.

Be sure to draw his name,

Then you say: Oh, you are so-and-so, I have heard of you, I am from a school,

..... wait, wait,

And then where did you meet,

Just to say hello,

You said, hey, do you remember me, the one who sent the wrong message last time,

That's pretty much it,

I don't know.