I thought villagers spawned under the right conditions?
I play on a server where the spawn was located at a village. Apparently all the villagers died before I began playing. Now I'm the only one left in the starting village, but no new villagers have spawned even tho all their houses are still here (with intact doors and roofs). Why don't they ever spawn? What am I missing? Do villagers only spawn if there are a male and a female villager to spawn them (LOL, but it would make sense, right)?
If all the Villagers died then what you have to do is either transport Villagers from other villages or convert zombie Villagers into normal villagers by curing them.
You need a minimum of two Villagers for them to breed, and the conditions for the Villagers must be properly set up:
1. Villagers need houses that are defined to be a house according to Villager breeding rules. If the house they could live in doesn't qualify as a house they won't use it and it doesn't count as a part of their maximum potential population, so if some Creeper blew up part of a house you would need to fix it first before they'll breed in it.
2. They need access to all doors in order to breed successfully and not pile up at one particular door. Versions 1.7.10 and thereabouts had broken or incorrect Villager breeding mechanics meaning that all of the Villagers would clump around one door and go nuts trying to open the one door. If you happen to find a situation like this when your population reaches a certain number, breaking and replacing the door they keep using sometimes fixes this.
They also were not correctly considering houses that spawned in a Village as houses and you would certainly have some work cut out for you if you wanted to fix things.
Have you checked with the server admins to see if they intentionally shut down the Village for some reason? Since you're on a server, it's certainly possible there was an issue with the Village at spawn and they simply removed or deleted all the Villagers.
Villagers don't naturally spawn in villages, they are generated once when the Village is created, but after that no new Villagers will naturally respawn there, they will only breed to repopulate a village if breeding conditions are right. This is a design decision by Mojang, AFAIK.
You should try to find the conditions for Villager breeding in the Minecraft wiki, and discuss with the server Admins if they want Villagers in the spawn village, as often they are removed for one reason or another.
Cheers ...
BrickVoid