There are a number of YouTube videos that suggest removing the batteries, then washing the keyboard in a dishwasher without soap (and without JetDry please), then drying it for four days or so in a warm location.
I don't think I'd go so far as to put it in a dishwasher, but you could put it in a container and add distilled water, then press each key a few times to help the water circulate underneath each key to help wash away whatever gunk you spilled on the keyboard. Change the water and do it a couple more times to remove as much of the sticky stuff as possible. Then dry for four days in a warm area, or use the 'put it in a bag with rice' trick.
I'd do this only if I'd given up and was ready to buy a new keyboard. Sort of a last ditch attempt to try to save the keyboard. If all else fails, take it completely apart and sell the pieces on eBay to others who need the parts!