Leave the pump alone to allow it to cool to auto-reset the thermal protector if the pump won't run. Heavy usage may trip the thermal protector.
Change the fuse or reset the circuit breaker if the pump isn't functioning at all. Inspect the power supply or generator capacity to ensure your power source is sufficient to handle the load.
Inspect the check valve and adjust it so it's installed correctly if the pump isn't delivering liquid properly. The check valve keeps the proper amount of pressure in the system so the pump functions normally.
Pull the pump out of the ground and clean out any debris if it is clogged and no liquid is being pumped. Lower the pump further into the ground if it isn't completely submerged.