Welcome to the forums!
I'm sorry for the current situation you are in. Since your budgies are in a place which is very difficult to reach, you may need to use a ladder and choose one of the longest perches you have on the cage to make your budgies step up onto it.
Even for untamed budgies, they can react and step up automatically the moment a perch is in front of them. During this entire process you must be careful as in to avoid sudden movements that can frighten your budgies and if they step onto the perch, it's important to very carefully lead them back to the cage.
If possible and in order to facilitate this, you can also place the cage as high and as close as possible to the beam where your budgies are. You can place a bowl of water and another bowl with food on top of the cage to entice them to land on it.
If the trick with the perch doesn't work, you can try to get them with a net or the help of a light cloth.
I hope very soon your budgies will be safely back on their cage.
Since you are new to budgies, the information on the several articles and sticky threads located at the top part of each section of the forums will be extremely useful as you become more familiar with the species.
Be sure to pay special attention to the Diet and Nutrition and the Taming and Bonding section of Talk Budgies.
Best of luck with your new budgie friends!