@Paul1432 I have had this situation a couple of times. I contacted Airbnb , they contacted the guests, and the guest then responded to me quite quickly. In both instances, there was nothing nefarious or "scammer" about the guest- One had been away at a workshop the week before her reservation, where there was no Wifi, the other had had a death in the family and checking her Airbnb messages was not exactly a priority.
In both cases I would have tried calling the guest myself, but both were on the other side of the planet and I don't have a phone plan that enables me to do that.