Did you check the kill switch by the hand grip? May have gotten flipped in the process of covering it up. Aside from a simple issue like that or an empty fuel tank you will need to do a little troubleshooting.
Verify there is spark. This can be done easily with an extra spark plug, or by removing the plug and sticking it in the plug boot, and touching the spark plug nut/threads to a bolt in the frame while you crank it over and you will see the spark jump the electrode gap. (if the plug wont stay touching the bolt, hold the thick part of the rubber boot)
The air filter shouldn't have got wet, but if you have spark I would pull the cover and make sure there isn't water sitting behind the filter.
You can verify there is fuel in the carb by turning the slotted screw on the bottom of the fuel bowl one turn counter clockwise while watching the clear tube by the carb to see if fuel begins to enter it. Once you see fuel in the tube close the screw back, but not too tight.
Hope you find the kill switch flipped, but if not you'll find the problem checking spark, air and fuel.
