Will it wash? But not pump? If that is the case then the dump solenoid is fried.
If it will not wash or pump the you have a bad door switch most likely.
The motor in your DW is a one directional motor.In the business it is affectionately named a "Sidewinder". The motor goes in the same direction all the time. As it Wash's the dump valve is closed and the water is diverted to the nozzles where it dispenses water on the dish's. When it comes time for rinse the drain solenoid opens the flap and the water gets dispersed out the drain hose.