BEWARE OF RABIES! DANGER TO LIFE
The symptoms you describe, the lack of motor control, the unawareness, staring into nothing, not being able to drink and eat on her own, could all be symptoms of rabies.
Rabies is 100% lethal to all infected humans and animals that are not vaccinated. If you're not vaccinated, please get the vaccine for you and your family as soon as possible. The rabies vaccine is the only effective treatment and it's still effective after you were infected and before the first symptoms set in. Even if you were vaccinated in the past, let your doctor check that the old vaccine is still effective and refresh it just in case. If this puppy indeed has rabies and infects you, there is no way to save your life as soon as you feel the first symptoms. That will be a fever and/or tingling at the site of infection (usually a bite or other wound).
(In the recent 10 years there have been several accounts of people surviving rabies. All of them have been only partially vaccinated and all of them retained very severe brain damage or died a few months later. There is no report of someone without any antibodies ever surviving. So even if you "survive" rabies, you won't ever be healthy again.)
Rabies is spread when an infected animal bites or scratches a human or other animal. Saliva from an infected animal can also transmit rabies if the saliva comes into contact with the eyes, mouth, or nose. Globally, dogs are the most common animal involved. In countries where dogs commonly have the disease, more than 99% of rabies cases are the direct result of dog bites.
You must separate the puppy from all other dogs and especially humans and children to avoid even more infections. Protect yourself from sudden, unforeseeable bites. The virus replicates in the nervous tisseus, including the brain and spinal cord and is eventually shed in the saliva of infected animals. Rabies is NOT found in the urine or blood of infected animals. You must always wash your hands and all objects that came into contact with the puppy with lots of soap, or better a 70% ethanol or phenol solution (many hand sanitizers are based on ethanol; read the list of ingredients to make sure). Be aware that the disinfectant must be applied for a prolonged time (most often several minutes) to be effective and you must apply more sanitizer to your hands until the required time (read the package leaflet) is over.
Rabies has many non-specific signs in animals that may be hard to detect in the beginning or can be confused with other signs. If the puppy becomes aggressive or has foam or thick saliva on its mouth, it could indicate that it has rabies, however, this can only be confirmed after a post-mortem laboratory test has confirmed the presence of the virus. Unfortunately, if the animal is in fact rabid and clinical signs have manifested, the mortality rate is near 100% and the animal will die from the disease.
Also keep a watchful eye on the other 2 puppies. They may be infected as well, but may not show any symptoms yet. If they are infected, they start shedding viruses (read: they could infect humans and other animals) before they show the first symptoms. If you can afford the treatment, get them vaccinated against rabies ASAP.
I hope very much that I am wrong with my assumption, but in case this puppy does have rabies, please be extremely careful and don't endanger your own life for the life of an animal you won't be able to save anyways.
There is a global charity (Global Alliance for Rabies Control) that specializes in rabies elimination in all rabies-endemic countries. It offers free online courses to teach you more about the disease and to raise awareness about the disease. You can learn more about rabies and help prevent eliminate the disease globally. Check out there website here: https://rabiesalliance.org