You have to get the budgie to drink.
Does it like vegetables? Giving it watery vegetables like Romaine Lettuce and cucumber will help.
What is the bird's name?
Try misting some of the budgie's toys lightly with water to see if it will lick the water off the toys.
Prepare the Guardian Angel or Pedialyte and offer it to the bird.
If the budgie likes bathing and you offer it a shallow dish of water it will probably drink from the dish before bathing in it.
The most important thing is that the bird stay hydrated.
If you aren't confident in ensuring that at this point, then call the vet back and ask about having him/her administer fluids to the budgie.