That does not bode well, @Sarah1342. Sounds like something has happened. Is it possible you have two accounts? That has happened to some people by accident. They used Facebook for a sign-in, then Google, that sort of thing.
If you don't think that is the problem, you will need to get in touch with Airbnb. Since the trip is not showing up, you cannot use the button on the itinerary for contact. Do you still have the email telling you that you are booked? That will help with reservation number, etc. You can try googling the phone number for the US, or, better yet, use Twitter. Send a direct message to AirbnbHelp. If you don't have a Twitter account, it is worth setting one up just for this. It's free.