The problem is that you aren't closing off the parentheses: (There is nothing wrong with this statement or (still nothing wrong)) Just delete the excess parentheses

function Move(msg)
    if msg == "w" or "W" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (0, 0, -0.1, 0)
    elseif msg == "a" or "A" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (-0.1, 0, 0, 0)
    elseif msg == "s" or "S" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (0, 0, 0.1, 0)
    elseif msg == "d" or "D" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (0.1, 0, 0, 0)
    end
end

script.Parent.Parent.Parent.Parent.Chatted:connect(Move)

The Second problem is your if statements. You have an or there, it's going to always move down -0.1 no matter what. Since it is basically saying: "Press lowercase w to do this, or if 'W' is real then..." W is real, or not nil, so it will always run! To solve this just add msg == in front of "or", but it might make the script seem too long, instead we will say: "If the lowercased version of msg is 'w' then..." We will be using string.lower()

local text = "HI"
print(text:lower())
print(string.lower(text)) --Both say "hi", so it turns "HI" into "hi".

Final Product

script.Parent.Parent.Parent.Parent.Chatted:connect(function(msg) --Anonymous functions :3
    if msg:lower() == "w" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (0, 0, -0.1, 0)
    elseif msg:lower() == "a" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (-0.1, 0, 0, 0)
    elseif msg:lower() == "s" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (0, 0, 0.1, 0)
    elseif msg:lower() == "d" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (0.1, 0, 0, 0)
    end
end)

Hope it helps!

Your problem here lies within your if statements. You need to completely redefine each piece before or else it won't work correctly. You had this for each one:

if msg == "w" or "W" then

You need to redefine the first part like this:

if msg == "w" or msg = ="W" then

The way you had it, the game was checking to see if "W" was true, so it automatically fired the first time on W, which makes it go up.

Now to implement the fixed script. I went through and fixed all of these for you, so here ya go:

function Move(msg)
    if msg == "w" or msg == "W" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (0, 0, -0.1, 0))
    elseif msg == "a" or msg == "A" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (-0.1, 0, 0, 0))
    elseif msg == "s" or msg == "S" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (0, 0, 0.1, 0))
    elseif msg == "d" or msg == "D" then
        script.Parent.Position = script.Parent.Position + (UDim2.new (0.1, 0, 0, 0))
    end
end

script.Parent.Parent.Parent.Parent.Chatted:connect(Move)

Also, you could just do this for checking each:

if msg:lower() == "w" then

This isn't required, but it's simpler than your method. Both work however

Anyways, the script should work now. Hope I helped, and if you have any further questions/problems please leave a comment below :P