2000 Astro,no pwr. brake or steering?

  Hello Everyone,  I have a problem and was hoping someone can shed some light on it!  I briefly got stuck in the snow the other day and afterwards the power steering and power brakes went out all at once! At first  i thought  it was the belt that broke but after investigating it seemed to be working fine, it didn't seem to be slipping, the water pump and alt. were working fine , theres fluid in both the master cyl. and steering pump? can't figure it out? could it be some sort of vaccuum leak?  the brakes do work , the same way when the vans not running!  any advice would be appreciated!

 The problem turned out to be a broken  pully shaft, once i took off the belt ,i was able to pull the  pully and shaft out of the pump, the steering pump acts like a brake booster, it also controls the power brakes. called "hydro boost"