Registration is closed
Maybe you wanted to compete in a certain event but the registration closed before you got to signing up. In this case, you are always free to reach out to the organizer of the event, however, it's important to note that the organizer don't have any obligation to let you register past their last date.
They have full control and ownership of their event dates and if you missed the last date, there are no guarantees they will let you in anyways.
We (Smoothcomp) can't do anything in this case. As mentioned, you can always reach out to the organizers and ask, but it's up to them whether you'll be let in or not.