"2 is not a valid member of IntValue" ?

Not quite sure why you have the ["2"] there, as F.2.Value should work just fine? From my knowledge you only use the brackets when you are referring to a table.

In example:

local Table = {
    ["Value"] = 1,
    ["Noogin"] = 2,
    }

print(Table["Noogin"])

That'd print "2".

But back to the script, this is what Caster was referring to:

local Dad = game.ServerStorage.PlayerData:WaitForChild("Dadithan", 20)
local F = Dad.Inventory
local Number = F:WaitForChild("2", 20)

function si()
    if Number.Value == 1 then
        Number.Value = 100
        Number.Metal.Value = 14
        Number.Wood.Value = 15  
        Number.Name = "40"
    end
end

si()

I'd suggest learning tables as that's a more secure and efficient way of doing it, however if you feel that you prefer this method then by all means.

I'll give a example of what the script would look like if it used a table: (Assuming that the "Number.Value" is representing "Money" and the Number.Name is representing "Age" as I have no idea what your doing with them).

local PlayerData = {
    ["Age"] = 0,
    ["Money"] = 0,
    ["Metal"] = 0,
    ["Wood"] = 0,
    }

local function DoCheck()
    if PlayerData["Money"] == 1 then
        PlayerData["Money"] = 100
        PlayerData["Metal"] = 14
        PlayerData["Wood"] = 15
        PlayerData["Age"] = 40
    end
end

--To add simply change the data like so, or use this function
local function AddToData(Value, Count)
    PlayerData[Value] = PlayerData[Value] + Count
end

--These two will do the same thing, but it's quicker to simply call the function
AddToData("Money", 50)
PlayerData["Money"] = PlayerData["Money"] + 50

With this method you don't have to wait for anything as it's already loaded by the time it hits the function, plus (Low level) exploiters can't simply edit the value to add to a stat.

If this is unhelpful, just let me know and I'll try to correct it.