If you try to add the contact to a new group, you will receive an error message like "Couldn't add participant". 1. Communicate via Group Chats
Very rare, but if you believe it was accidental: how to be unblocked on whatsapp
After a few weeks, you may send polite message via another medium — SMS, email, or a mutual friend — but only if you have a pre-existing, respectful relationship there. If you try to add the contact to