Get formula.
Also, you cannot take away a new puppy who is only 4 weeks old. Did you get her from a breeder? RETURN her immediately! This dog is going to have serious issues, like separation anxiety, social issues, etc!
Here is a recipe for formula you can use from:
http://leerburg.com/bottlefeeding.htm?set=1
10 oz. of canned evaporated milk OR whle goat's milk (not pasteurized cow's milk - this will cause scowers - dogs cannot drink normal cow's milk. Dogs cannot drink 1%, 2%, Skim, or Whole milk.) Whole goat's milk is by far the best to use. Walmart sells both evaporated milk, whole goat's milk and evaporated goats milk. Make sure you are using EITHER evaporated milk OR whole goat's milk. Do NOT use sweetened condensed milk!
3 oz. sterilized water (baby water OR boiled water that is then cooled). This is NOT needed if using whole goat's milk.
1 raw egg yolk.
1 cup of plain yogurt (avoid skim or fat free if at all possible).
1/2 Tsp Karo Syrup or Corn Syrup (NOT HONEY!)
**If you cannot find Karo or Corn syrup where you live, you can do a Google search for “substitute for Karo syrup” and get some options. When I Googled “substitute for Karo syrup", here is what I came up with - 1 c Karo can be subbed with 1 c white sugar and 1/4 c hot water (Cook it to dissolve in the water best you can get it to. Depending on the recipe, if you need the sugar to be completely dissolved you might need to add a bit more water.)
Place ingredients in a blender and blend or use a wire whisk. Be careful to not over blend and create a milk shake full of bubbles and then tube bubbles into the puppy.
Keep cool and discard leftovers after 7 days.
Warm formula to body temperature (dogs are around 101 degrees). Discard any un-used formula. This is a thick mixture - use a stomach tube to tube feed or enlarge the hole in the nipple for easy access for the pup