Here's the code for when a player enters:

nensaves = game:GetService("DataStoreService"):GetDataStore("NenCharacterSaves")

game.Players.PlayerAdded:connect(function(plr)
	local playerkey = "user_"..plr.userId
	
	
	local SaveOne = Instance.new("StringValue",plr)
	SaveOne.Name = "Save1"
	
	local statsz = Instance.new("IntValue")
	statsz.Name = "leaderstats"
	statsz.Parent = plr
	
	local RunSpeed = Instance.new("NumberValue",SaveOne)
	RunSpeed.Name = "RunSpeed"
	RunSpeed.Value = "45"
	
	local CharaHealth = Instance.new("NumberValue",SaveOne)
	CharaHealth.Name = "Health"
	CharaHealth.Value = "100"
	
	local NenMastery = Instance.new("NumberValue",SaveOne)
	NenMastery.Name = "NenMastery"
	NenMastery.Value = "0"
	
	local Strength = Instance.new("NumberValue",SaveOne)
	Strength.Name = "Strength"
	Strength.Value = "0"
	
	local NenCapacity = Instance.new("NumberValue",SaveOne)
	NenCapacity.Name = "NenCapacity"
	NenCapacity.Value = "100"
	
	local Jenny = Instance.new("NumberValue",SaveOne)
	Jenny.Name = "Jenny"
	Jenny.Value = "0"
	
	local Enhancer = Instance.new("NumberValue",SaveOne)
	Enhancer.Name = "Enhancer"
	Enhancer.Value = "1"
	
	local Transmuter = Instance.new("NumberValue",SaveOne)
	Transmuter.Name = "Transmuter"
	Transmuter.Value = "1"
	
	local Conjurer = Instance.new("NumberValue",SaveOne)
	Conjurer.Name = "Conjurer"
	Conjurer.Value = "1"
	
	local Manipulator = Instance.new("NumberValue",SaveOne)
	Manipulator.Name = "Manipulator"
	Manipulator.Value = "1"
	
	local Emitter = Instance.new("NumberValue",SaveOne)
	Emitter.Name = "Emitter"
	Emitter.Value = "1"
	
	local Specialist = Instance.new("NumberValue",SaveOne)
	Specialist.Name = "Specialist"
	Specialist.Value = "1"
	
	local DailyBonus = Instance.new("NumberValue",SaveOne)
	DailyBonus.Name = "DailyBonus"
	DailyBonus.Value = "0"
	
	local Rank = Instance.new("StringValue",statsz)
	Rank.Name = "Rank"
	Rank.Value = "Trainee"
	
	
	
-- 
	
	if nensaves:GetAsync(playerkey) then
    	local statsload = SaveOne:GetChildren()
	for i = 1, #statsload do			
	statsload[i].Value = nensaves:GetAsync(statsload[i].Name)
	
	end
	end
	
  
	
	
end)

And when they leave: 

nensaves = game:GetService("DataStoreService"):GetDataStore("NenCharacterSaves")

game.Players.PlayerRemoving:connect(function(plr)
	
	
	
	
	
	
	
    	local statstorage = plr:FindFirstChild("Save1"):GetChildren()
for i = 1, #statstorage do
	nensaves:SetAsync(statstorage[i].Name, statstorage[i].Value)

	
end
print("saved 'em")	
end)

For some reason, the stats will not save. Everything else works fine. I've already checked to make sure that DataStores were enabled on the game's page.

Anonymous