How do I make it so when I press a button it only triggers untill i press it again?

Its hard to understand what you want but ill make a wild guess you want some code to be executed when you press a button and continue to be executed until you press it again? One way is to use a coroutine that gets started the first time you click and stopped the next time. http://docs.unity3d.com/ScriptReference/Coroutine.html

No i want the code to only execute once when i press a button, so say if i hold the key "t" down it will still only execute once, and it will keep the light in that same state until "t" is pressed again. I hope this is more understandable:/.