My husband's 2000 Dodge Ram suddenly lost all power steering...when checking the fluid level, he noticed it full...but appears to be leaking...any thoughts?

 

Bad pump or drive between vac pump and steering pump failed? Possibly the steering box has an internal leak not allowing the pressure to assist and work it's magic? That could be a place to start?

 

I went thru the same thing and lived with it for a while until I hit a pole on a bend...that sucked. After body repaired and replaced... 3 power steering pumps, 1 steering box and 1 stabilizer later it seems to be working ok. It started with the stabilizer being 'flattened' which over-worked the steering box over time which totally screwed up the pump. Replaced the lines first (very inexpensive) for I was informed that some of the lines collapse over time - the rubber lining breaks down and can clog the pump. Might be a good place to start for ya.
You say leaking...from where?