My son played with his new duplo car in the sand and now the wheels are not turning. How can I fix it?

http://godarmachinery.com/v/DBM-400%20Instruction.pdf

https://www.colorprintingforum.com/threads/duplo-collator-error-codes.17759/

Firstly please use the queens english as lug means to a slang word to carry ,or a worm in the sand used as fishing bait ,so yes you have removed the the four wheel nuts ,leave the middle one alone as that holds the drive shaft on ,whats happening is no doubt you have a alloy wheel rim and its corroded to the hub, now make sure wheel is off the ground and then place a axle stand under the chassis to support the weight -now the fun part place aplank of wood against the inside of the wheel lay underneath and hit the plank with a 7kg(14lb) hammer ,you stated this is your sons car and he cannot change his own wheel ,a daughter maybe --but a mother changing a sons wheel on a car ,now i have heard it all?? once the wheel is removed make sure you put some grease where the alloy contacts the steel of the hub to ensure it doesnt corrode up again then send the prodical son to a car repair course at the local college .Mother changing a sons wheel ---iam speechless as i just dont beleave what i have read to be true?What will happen if and when he ever gets married --Does he know enough to make you a grandmother ? sorry to be facietious but?mum changing a sons car wheel

Did the key work before ? If so it is u need a new key cut put key in and turn and hold it there while turning steering wheel left &right quickly it will go but this is a quick fix don't rely on it

Target have a nice basic model for under $25.

http://www.target.com/p/sand-water-wheel-play-table/-/A-12703401

But if you are looking for something a bit fancier, you could try this one from Amazon;

http://www.amazon.com/Step2-WaterWheel-Activity-Play-Table/dp/B000641DPQ

YOU CAN DOWNLOAD IT VIA WWW.GETMANUAL BUT HAS TO PAY SMALL FEES VIA CREDIT CARD

DUPLO-C120

Turn the wheel while turning the key will unlock the wheel wiggle the wheel while turning the key.

If the wheels don't turn there may be sand in the notches on the wheels, the notches may be worn off, if their is sand or dirt in the paddel wheel jet that will keep the unit from turning and again no wheel movement. All of these problems they can check in your local pool store. Stores will generely check your unit out and fix what is needed for just the price of parts to fix it when you bring it into the store.
If you have no water flow to the unit this will also stop things from working so be sure to check your finger screen before you do anything.

the controls are VERY sensitive for this game.
But for the "circual driveng no matter what" is more like a problem with the wheel itself rather than the game.
I suggest returning the wheel and buying a new one or simply not using it and playing with just the Wii-mote itself.

I hope this helps!