Job made a big deal of putting in two full weeks’ notice, so I did, and still get punished?

I respectfully let my supervisor and scheduler know that I was putting in my notice of two full weeks, and now they won’t answer messages at all. Even work related, time sensitive questions go unanswered. Any suggestion on what I should do? They also never had me fill out tax forms or a contract so they’re paying me under the table. Because of that, I’m scared they won’t give me my last check if I act out at all.