attempt to index global 'f' (a nil value) how to fix?

Your problem is game.Players.PlayerAdded:connect(touched) If it's a brick you touch for it to teleport you, put that script inside of a brick and replace that line with:

script.Parent.Touched:connect(touched)

Then in the code, you need to make sure f is a true value. Add if not f then return endto make sure the rest of the code will not run.

Final code:

function touched(touch)

while (h == 1) do

f = script.Parent:FindFirstChild("Humanoid")
if not f then return end


f.Position = Vector3.new(0,55,0)



wait(0.1)   

end 


end

h = 1
script.Parent.Touched:connect(touched)