I have them in a safe area and still despsawneds or gets killed i already had this problem before and i was alerted by my other roommate that it happened again
I know it's a pain, but if you name them using a name tag, that ensures that they won't des pawn. Of course, this is only efficient if you only have a few villagers.
hmmmm. other players can't kill your villagers, anti grief protects them from that. Is there any way for the villager to have escaped and fallen off your island?
Put another layer of blocks around the "cage" you have for them. That should fix them falling through the floor.