HI @Bruce69,
Welcome to the Community Center!
Unfortunately one of the penalties of a host cancelling a booking is that the dates of the original booking are blocked and you therefore cannot have another reservation then. This is why you are unable to edit the prices for those dates. This Help Guide outlines the penalties for a host if they cancel.
As you are a new host and you weren't aware of the penalties, you can contact Airbnb and see if they might waive these penalties this one time, there is no guarantee this will happen however. This Community Help Guide explains the best ways to get in touch with them.
Kirstie