facebook help pleaseeeee?

So I got a facebook message from someone and I think its this person that I really need to talk to but I can't message him back cause he blocked me a while ago but I swear its him ! What do I do? I tried sending a message asking who it was but the message couldn't send because I was blocked . Please what do I do. I desperately need to talk to him and I think it might have been him pleassseeee help