Anyone know a way to keep this attached?

One day the cover was off. I went into the pool and tried to reattach with screws but the part that the screws go into is gone. I unscrewed the other to compare and the other one has parts where the screws go into. I'm assuming those parts are long gone. Any idea if those can be replaced for the screws to screw in again. Or anyone know of a good adhesive that I can just glue it down? Any help would be very appreciated.