After the lawyer's letter was sent, the other party disappeared, the phone was not answered, and the text message was not returned. What should I do?

I think, whatever the relationship, you only need to make two phone calls and send two text messages. If he sees it, he will always call you or reply to text messages if he is interested. If he really doesn't want to answer or reply, then you will get the same result by making a hundred phone calls and sending countless messages, and it will only be annoying in the end.