On apps like WhatsApp, unblocking someone restores their ability to see your "Last Seen," profile photo, and status updates (assuming your privacy settings allow "Everyone" or "My Contacts").

When a contact is blocked, they cannot send you messages. If they tried to message you while they were blocked, those messages are lost forever . They will not suddenly appear on your phone after you unblock them. You will only receive new messages sent from this point forward.