Hello @Yvette208
Welcome to the the community boards.
Firstly I need to tell you for the future, when you need specific individualised help, it's best to create a new post or thread. You have tacked your question onto a thread that was created over 2 years ago - it would be very likely that no one even saw your question.
This community is just a group of interested guests and hosts trying to help each other out - we have nothing to do with the administration of airbnb.
Every host that I know is under the very firm impression that airbnb do not actually take any money from a bank account or credit card for a security deposit. They might ensure there are sufficient funds, but they do not withdraw the money. That is what we have always been told, and this has been my direct experience both as a host and as a guest.
If you cannot even find the history of your past reservation, are you absolutely sure that you booked through the airbnb platform? Could it have been VRBO, or STayz? ( They DO take and hold the security deposit)
If you are sure it was via airbnb then your past reservations should still show. Go to your profile, select travelling, select trips - and under the heading "where you've been" your past reservations will show. I can still see my reservations from 2015. With that information, click help and follow the prompts to get a phone number to call airbnb to discuss.
Hope this helps
Regards