So I Got This Script From Youtube and it wont work. I’m guessing its outdated?

local DS = game:GetService("DataStoreService"):GetDataStore("Data")

game.Players.PlayerAdded:Connect(function(plr)
	
	local l = Instance.new("Folder")
	l.Name = "leaderstats"
	l.Parent = plr
	
	local v = Instance.new("IntValue")
	v.Name = "Energy"
	v.Parent = l
	
	local file = DS:GetAsync(plr.UserId)
	
	if file then
		v.Value = file[1]
	end
end)

game.Players.PlayerRemoving:Connect(function(plr)
	DS:GetAsync(plr.UserId,{plr.leaderstats.Points.Value})
end)

This is your problem:

At line 21, you are calling :GetAsync() instead of :SetAsync().

here is the fixed script:

local DS = game:GetService("DataStoreService"):GetDataStore("Data")

game.Players.PlayerAdded:Connect(function(plr)

    local l = Instance.new("Folder")
    l.Name = "leaderstats"
    l.Parent = plr

    local v = Instance.new("IntValue")
    v.Name = "Energy"
    v.Parent = l

    local file = DS:GetAsync(plr.UserId)

    if file then
        v.Value = file[1]
    end
end)

game.Players.PlayerRemoving:Connect(function(plr)
    DS:SetAsync(plr.UserId,{plr.leaderstats.Points.Value})
end)

Note that sometimes roblox doesnt really save data is studio, but it does in the actual game.