Andrea, sorry to hear about your situation. Here are some suggestions:
1. When you say "just became illegal" I assume you meant your local government has passed a new law to ban short-term rentals. If so, look into how it was passed. Was there adequate notice of the meeting, consultations with local home owners, neighborhood associations, realtors, property managers, tourist associations etc?
2. Organize. Get together with other hosts. Form a group. Reach out to other groups or individuals opposing this ban (small businesses, chamer of commerce etc). Get statistics - how many hosts in your area, estimated contribution to local economy, estimated loss in taxes (if hosts are paying a "hotel tax"), are there adequate number of hotels in your area, etc.
3. Meet with your mayor and City Hall representatives and present your case for fair regulations (maybe a limit on number of nights allowed each year that most can live with) instead of a total ban, which is extreme.
4. Run for office yourself.
Good luck,
Peter.