@Susan753, I am so sorry this has happened to you!
I hope AirBnB can help you get your calendar fixed so you can host people for a good price for the Superbowl!
The topic I wanted to ask address was the whole "hacking" your account thing. What evidence was left that makes it clear he hacked your account?
The reason I ask is that I remember some people recently having trouble with glitches in the AirBnB system, and I wonder if the disappearance of your Feb prices was due to the same system glitches. It takes a lot to convince AirBnB to make a change to their policies about cancellations, and I want you to have the strongest possible case to bring to them.
To back up the claim about hacking, maybe you can ask them if they have logs of who accessed your account. If someone else accessed your account, hopefully AirBnb has records of someone logging in to your account from a different location, or a log of when your prices were last changed.
If they do keep a log of price changes, maybe ask them to look into the logs of the time you made your own changes. See if the log shows the price changes being properly saved. Maybe there was a system glitch that caused your changes to not save correctly. You are looking for anything to help explain that the cancelled reservation is not your fault.
Best of luck with this! I hope you get a good result from talking to them!