It depends how many you save,
if you saved very few,
it will take a while for the people to come back,
and it will never have as many people as it did before.
Try sleeping in-game for a few days and it might restore fairly well.
There is no way to become good,
once you are evil at the end of the game,
unless you want to go to every person individually and become friends with them.
Another thing i was thinking of is buy all the houses in the game and charge lowest price for rent,
and your renters will slowly start to like you.