Power Steering Problem

My daughter had a power steering leak and neglected to have it fixed just replacing the fluid when it ran so low as to cause problems for a long period of time. She finally had a hose replaced but a few weeks later, the power steering went out completely. No noise, no nothing comes from the power steering unit. I have a sneaking suspicion that the pump is bad now. My questions are:

1) Are there any other possibilities?
2) Most importantly, because this is most likely the problem as I see it, how hard is it to replace the power steering pump? An outline of the procedure to give me an idea would be helpful.

Thanks in advance,
Dave in NC

Other than steering pump, you should consider checking the gearbox in the rack pinion also. It maybe bind and can't steer. That may need a replacement if it binds. I have never change a RWD car steering pump before and I can't say for sure that it's hard or easy. I do have PDF manuals for 03 M45 if thats what your daughter has.