Your code is on the right track, but it isn't working the way you intended it to.
Below is the correct code. Notice how I stored the raw_input under a variable. That way I can make changes to it as necessary. Also, when I called the function, I called it using the built in python keyword: raw_input, as a parameter.
This should do what you wanted it to do. Let me know if it doesn't. Otherwise, have a great day!
r = raw_input("Desea apagar la PC?")
r = r.lower()
print "Apagado cancelado!"
print "Lo siento, no te entendi."
Also for some strange reason. Using characters like í and ¡ prevent the code from working. Not sure why, but besides that, the code should work flawlessly