i cleaned my wireless keyboard with windex and now it won't work

To clean the keys these work very well....

Don't know about 2013 but Windex used to contain ammonia solution. Ammonia disolves copper. Copper is required for critical keyboard connections. Therefore I suspect the KB is dead.

They are nearly impossible to take apart, so it's likely time to go shopping.

You should never clean any computer component with any kind of solvent. Windex does indeed contain ammonia, and it is never recommended to come anywhere near electronics (it will ruin a computer monitor screen too - wrecks havoc on the various anti-glare and other coatings on monitors, TVs and such).

As mentioned, you have very likely ruined the keyboard now.

Cleaning Apple products:

http://support.apple.com/kb/HT3226

Ever so slightly damp cloth (if even damp) to clean these keyboards.

I have used Windex or a Windex-like product on all my keyboards without any problems. Except I didn't spray it directly on, but instead used a very lightly Windex-dampened paper towel or Q-Tip,which caused absolutely no harm. I supspect you got it much too wet and it's gone into the contacts. If it isn't allowed to get into the contacts, it's perfectly safe for the plastic. Of course, don't use it on the screen.