My run scripts cooldown is always failing after it works for the 1st time working how do I fix it?

if script.Parent.Disabled == true then
	wait(5)
	script.Parent.Disabled = false
	wait(0)
	script.Parent.Disabled = true

my script

game:GetService("UserInputService").InputBegan:connect(function(input,gameprocesed)
	if input.KeyCode == Enum.KeyCode.LeftShift then
		for i = 1,16 do
			wait()
			game.Players.LocalPlayer.Character:WaitForChild("Humanoid").WalkSpeed = game.Players.LocalPlayer.Character:WaitForChild("Humanoid").WalkSpeed + 1
		end
	end
end)

game:GetService("UserInputService").InputEnded:connect(function(input,gameprocesed)
	if input.KeyCode == Enum.KeyCode.LeftShift then
		for i = 1,16 do
			wait()
			game.Players.LocalPlayer.Character:WaitForChild("Humanoid").WalkSpeed = game.Players.LocalPlayer.Character:WaitForChild("Humanoid").WalkSpeed - 1
		end
	end
end)

game.Players.LocalPlayer.Character:WaitForChild("Humanoid").Died:connect(function()
	game.Workspace.Camera.FieldOfView = 70
	game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 16
	script.Disabled = true
end)

and the script I am trying to cool down (I stole it from someone as that was at times I did not know how to code)

If you want a cooldown you should probably use a debounce variable instead of disabling the script, as that stops the thread completely..

if debounce == true then
	wait(5)
	debunce = false
	wait(0)
	debounce = true
end