Received a notice of termination of registration for my wife's registration

[Wizard2021]

Hi I received a notice of termination of registration for my wife's registration because she did not apply for visa within 1 year of the notice that was sent. The notice was sent to me in April of 2020 according to this letter that I just got. But I actually never received any notice. I know that in April of 2020 there was a lot of problems with the mail in my area due to covid. The letter indicates that I can appeal this deciding if there was a reason beyond my control.

1. is that a good explanation for reinstatement?
2. where should I mail the letter?