Power steering not working?

My car's (1999 Chrysler Concorde 2.7L) power steering isn't working. The car was sitting for about a year and I have got it back to running. The power steering isn't working on it. When the car is running I can see inside the pump and see the fluid turning inside but the wheel is hard to turn unless driving at a low/high speeds. I'm wondering do I need a new pump or another problem?? Any help would be great thanks..