The best thing to do, is to probably put your controller in a bowl of rice, for a couple of hours, and if that's doesn't work then you might want to bring it to a gameing store to see if they can help you.
I know that Taylor's suggestion Sounds a bit extreme, but She is right. put it in either a bowl, or a bag of rice. make sure that the rice covers the controller completely and leave it there for at least 24 hours. the rice should absorb the moisture, and dry the controller. I have done this with my phone 3 times after it getting wet, and surprisingly, my phone still works. :)