I have water coming into the house so I know the well pump works fine. The problem is that there is no pressure in the pressure tank and the gauge is at 0. over the winter I ran the water to a steady flow so the pipes wouldn't freeze when the temps dropped to single digits what's wrong with the tank?

It may not be a problem with your tank, it could be a problem with your pressure gauges. It may have something to do with the freezing weather, that may have damaged the gauges.

Perhaps the tank is supposed to have air in it, but doesn't, so the gauge is reading zero. Does the tank have a valve stem on the top somewhere (bicycle tire stem)?

If you have water flowing, you at least have some pressure, near normal if the water flow is near normal. The air in the tank has nothing to do with the pressure, only providing a cushion to lengthen the pump cycles. When you turn the water on, the air in the tank expands to push the water out until the pressure drops to the cut in pressure, often 30 psi. The pump then runs, compressing the air until it reaches cut out pressure, often 50 psi, and shuts off. When the pump cuts off, the tank should go thunk in the bottom half and clang in the top half.

I agree you need a new pressure gage.