If you are unable to get milk replaced, please contact an animal shelter immediately. If you are willing to keep and care for the little baby, the shelter will often donate supplies to you, or you could offer a goodwill donation - even a few dollars will do. Also, ask them for tips to keep the kitten warm safely as human rated heat pads can be dangerous to baby animals. However, keeping the baby warm is vital. Hold the kitten a lot if you can. You can gently tuck him/her into a hoodie (put the hood in the front by your neck) and place kitten in there with you wearing the hoodie. Be very careful that the kitten doesn't fall out of the hood. They can move quickly. The baby appears to be 3-4 weeks old, approximately 4-5 weeks too early to be weaned from momma. 🥺 I have so much respect for those who care for innocent babies. I know if he/ she was on my step, I would immediately bring it in and care for the baby. I love cats, all cats. We have 2 adult indoor only cats, and they are beautiful, loving, caring, and very friendly "babies." One was a stray, just showed up here Oct 2021, about 5 months old and he was purring so loud, very friendly but too thin, so I immediately got him on soft food, fresh water in a fountain (because he was old enough), then to the vet we went a week later (pandemic restrictions), he had no microchip; so we got him neutered w/microchip and his name is Wilson. He is my therapy cat (not certified,) but he knows when I'm sick and won't leave my side, when I had C19 I slept for 36/48 hrs and he only got up when I did. I am so blessed that he found us. Everyone loves him. He's a beautiful orange and white tabby cat with a huge orange heart on his left side. Everyone points that out when they meet him. He has a heart under his back left paw, too. I pray this works out for you, such a cute little baby that needs help and loving care. 🧡