All the villagers in my realm have despawned. This is the third time there has been mass spawned. The last time it happened, there were many villagers ~ 10 villagers, with lots of defence, iron golems, walls around the whole town. It is unlikely they were all killed by mobs overnight without me realising. 

have also searched for an answer a few times and seems to have happened to a lot of other players with no satisfactory solution to fix it from happening or know why it's been happening 

name of the realm is MPH87. I don't own this realm though