Question
QUESTION: I am ready to turn my sprinkler off for the season but for some reason I cannot get the control box to open.  I've attempted to look & see if maybe a "key" that fell off but can't remember anything like that.  can you help me?

ANSWER: Katherine,

If you don't see a key slot in the front door then it doesn't require one.
The doors are sometimes hard to open. If you can tell what model or manufacturer you have I might be a little more helpful.
I realize most of that info is on the inside, but even the name on the outside of the box would help.

Matt

---------- FOLLOW-UP ----------

QUESTION: Matt,
Than you for responding. Here is a picture of one I found on Craigslist.  Small pix but maybe you can make it out.  The system was already installed when I bought the house & the previous owner did not leave any information. I can usually just pull the door open & push to close but it is really tight!!!
http://sfbay.craigslist.org/eby/grd/879144865.html
Any suggestions would be greatly appreciated.  I turned off the main water line going to the sprinkler until I can find a solution.
Katherine

Answer
Sorry to say the web link wouldn't open.
Controllers usually have a little tab which hold the door closed. It sound like your is just being stubborn.
You can try a little heat from a hair dryer or a hot towel. Don't over do it. It is an electronic device and cooks at about 170. The heat may soften/distort the plastic enough to allow you to open it.
Hope this helps.

Matt