why does our puppy don't want to walk anymore?

He needs to see a vet.

This does not sound like the fan DIDN'T hit him. It sounds like it DID hit him and he has spinal / neurological problems.

Please get him seen.

Add on -- ok if the fan didn't hit him, but there still seems to be a major problem that has started at the same time so please get him to a vet. As MamaBas said, laying down to pee would only be done when something was very wrong.

You certain the fan didn't hit him? Whatever the case, to make sure what he's doing isn't physical (break or other injury) you must get him looked at by a vet. If he's only young, it's extremely unlikely, I would have thought, he'd be so traumatised he'd not get up at all. And lying to pee is an indication he's in serious trouble.

he needs to see a vet immediately.

The quickest way to get on top of this will be to crate train her when you go out. You need a cage large enough for her bed and food/water dishes. Place it in an out of the way area where she will feel secure. Don't force her to use the cage. Initially use it for feeding and sleeping until she is used to going inside. Never punish her if you come home to a mess. It will only increase anxiety and make her more likely to mess next time. Dogs don't like to mess in their beds, so she is much less likely to have accidents when you go out if she is confined in the cage. When you get home let her outdoors immediately and give lots of praise if she goes. Once you have cracked the house training many dogs will choose to go in the crate as they treat it like a den. It should never be somewhere you send the dog as a punishment. After the baby is born it can become a refuge from your toddler. If you don't have any paperwork for the vaccinations it would be safer to get them done again. Worm an adult dog at least every three months, or more regularly depending on your vets advice for your local area.

Take him to a Vet. He may have injured his spine when he reacted to the fan falling.

I believe you when you say the fan didn't hit him. You wouldn't be asking us if the answer was that simple. I do think that maybe it was coincidental and that there is some other, unrelated problem. I would take him to the vet to have him checked out. I wish you the best..hope he's back to normal soon!

Have you tried massaging him very gently all over to check whether there is a bone fracture somewhere?

Even the fan didn't hit him, he could have jerked up and pulled a muscle or legament.

You don't sound as if he is in pain. Suggest you examine him all over yourself right away and note down his weird behaviour with date and time. This journal will give the vet a clear account of what he has been doing.

This could be a lot of things. If he is a big dog he may be having bone problems. Because there is some much unknown about this dog it is best to take him to the vet asap. If he not walking right there something really wrong.