i have a guest staying since yesterday, but now i just noticed that the request was cancelled but he still stayed there, so he has to pay me.. what can i do now?
contact Airbnb immediately and find out why this reservation is canceled. It may be their payment didn't go through or there were some other issues and Airbnb canceled his booking.
I would go there, speak with my guest, show him that he has no booking and ask him to pay me immediately in cash or to vacate.
If he doesn't want to do either of these two solutions I would call the police for trespassing.