Why would there not be any water cycling through our unit? When plugged in the unit just hums and doesn't run through any of the cycles. Put a new battery in it and reset all the settings. I have selected the "cycle now" button but nothing. Is there some kind of pump on the unit that is bad or a switch somewhere that needs replaced?

No pump on thhese units, water circulates via home water pressure. Sounds to me you have a stuck solenoid or timer. Many DIYers can do this type of repair, can you?