Hard to think he would have let his website expire. I don't really have much for you other than time to get a new CPA.
Definitely an odd situation. You’re probably going to have to move on. I wouldn’t wait more than a month. Websites can be auto-renewed so that they don’t expire.
Very, very bizarre.
You may want to contact the IRS and state to verify that 2017 tax returns were actually filed.
They were filed.
If it was me - I'd contact some neighbors of his business. Go to google maps and look at satellite picture and 'walk' down the street and see what businesses are next to his and contact them and ask, if the business is still in existence .
Put his name, city and 'obituaries' into google and see, if he's passed.
Read some of his previous BP posts and see, if in those threads, there are other people posting that seem to have a relationship with him and contact them.
Send a return receipt letter to him, so that you can see, if he signed for it.
Google his name and see if there're some accidents mentioned.
Something personal could have happened - like a family crisis, a health issue or even death.
I like @Michaela G. 's suggestion to contact the neighboring businesses - however, if he is a one-man shop, he might not have a physical office and work from home.
Since 2017 returns have been filed, you probably can afford to wait a little longer. Meanwhile, tax planning questions, if urgent, can be discussed with another tax professional.
I would find a new tax professional. Unless you hear from him soon with a good explanation it does not sound like someone whom is reliable.
Let's hope it wasn't that guy that was scamming people on 1031 exchanges. Robert Hetsler. He also wrote on BP and there's a long thread on him. He's in a coma
I will be mailing a letter today that will need to be signed for. No, it is not Robert Hetsler.