A standing baby is a good sign, but you've got to get that goat onto milk for it to grow strong and healthy. A few additions to what I've read above:
Long legs and hanging head are signs of
Floppy Goat syndrome, due in large part to mineral difficience in the mother during gestation. Goats need a much broader diet than sheep to fill more diverse nutritional needs. Think scrubby woods over pasture. If there is no access to this you need to supplement with minerals.
Is this a first time mom? First timers, especially young ones, often need help attaching with their young and getting the flow of nursing, so to speak. But you can help:
The above comment about putting mother and babies in a small stall is correct, making sure that Mom has food and water, and there is enough ventilation. The air bound ammonia from their waste is in much higher concentration near the floor where the young are, and it can be harmful or lethal at a high level. Cracking the stable door should be sufficient.
If I encounter a rejected offspring, I milk the mama and slather the baby in the milk. Goats have their "identity" (for lack of a better discriptive) wrapped up in their scent - so when the baby smells like mama, the mama will instinctively treat it like part of herself, letting it nurse.
I'll babysit them as much as possible for the first several days, going so far as to hold mama stationary and placing the baby underneath, brushing its face on the udder. The mama won't let much milk down under this stress, but it can help to get the mechanics down while they're getting used to it.
You'll know if the baby is getting milk because it's tail will flick about. Victory!
Last season, I had 2 goats born with FGS badly, unable even to stand and barely able to lift their heads. Each was utterly rejected by their first-time moms. Moms happened to be sisters. I was able to get them each their mothers' colostrum, which is crucial. One of them I nursed from the bottle for 4 days until it could stand, and then bonded it not with its mom, but with its aunt, using the above method. Worked like a champ, strong to this day. The other took 11 days before it could stand to nurse from the bottle, and there was no lactating mom available for it to bond to at that point. So I gave my four-year-old the responsibility of feeding it from the bottle until it was ready to be weened. This one is also doing well, but not as strong as the other. Also, it doesn't seem to know it's a goat - behaves much more like a dog, following me and my son around , scratching its wee horns on our sides. Both successes and joyful recoveries, but I will take a natural, goat-milk-from-the-udder-fed kid any day over a bottle-nursed, for strength and development.
Also a good not o check the udders. Blackened udders need a antibiotic, herbal or LA-200 if you wanna go that route.
I can add more as I think of it. Hope this helps!