It sounds unlikely that it is your water pump.If your water pump was not working your car would be overheating.I would look at the valve that is in your heater hose that turns the heat on and off.The cable that switches the heat on and off could have become disconnected under the dash or at the valve.The vavle could also be stuck and not open.Look at the small heater hose that goes to the firewall on the passenger side,try to move the valve by hand.Hope this helps.
Mark