@Pim36
If booked after 14 March:
The only option you have is the goodwill of the host.
If you can make the trip later, maybe the host is willing to reschedule the total(!) trip.
Otherwise cancel and except only the cleaning fee (if any) is refunded.
Added @Pim36 :
If you travel very soon to the capital Sofia, you maybe have seen on the news there is protesting and violence on the streets.
If you cancel, you could try to claim refund for "extenuating circumstances" (not Covid related):
https://www.airbnb.com/help/article/1339/how-do-i-file-an-extenuating-circumstances-claim