@Michelle4011 OK, what is your question?
If you are asking what happens, the answer is, the stay will be deemed to have started today unless the guest has officially applied to Airbnb to change the reservation, in which case you would have been asked by Airbnb to either approve or decline the alteration.
As it appears this has not happened, tomorrow you will receive your payout for this reservation as per the booking details. It will not be subject to your cancellation policy because the stay has technically already started, even though the guest isn't there.
The guest may ask for a refund for the night not stayed, and it is up to you to decide to either allow that or not.
In many instances Michelle a host will negotiate with the guest to refund a portion of the first nights rent and retain the remainder to cover preparation work that had been done for that night. You are not under any obligation to offer any sort of refund but, it's doesn't get the stay off to a good start if you don't, and it could lead a bad review if you refuse. just remember that.
If you and the guest arrive at an acceptable amount you wish to refund you go to the message stream with that guest and from the details pane at the right of screen select the 'Send or Request money' tab, put in the amount of money you are prepared to refund and that will be sent to the guests payment method and taken from from next hosting payout!
I hope this answers your question, if not can you please provide a bit more detail.
Cheers........Rob