The button should be removed when it's clicked, and sets the player's walkspeed to 16.. At the moment it does nothing :/
Button = script.Parent -- close button
Button2 = script.Parent.Parent.Parent -- removes the gui
function onClick()
script.Parent.Parent.Parent.Parent.Parent.Character.Humanoid.Walkspeed = 16 -- sets player's walkspeed to 16
Button2:Destroy()
end
Button.MouseButton1Click:connect(onClick)
The script is inside an image button, inside a frame, inside a Gui which is inside StarterGui

2 comments
Thank you! :)
In studio in the 'View' Tab, open the 'Output' window. This will (most of the time) find errors in syntax or stuff like that