Check the settings on your thermostat. Make sure the temperature control selector is set above the current room temperature, and the system switch is on the HEAT or AUTO position. The fan switch should be set to ON for continuous airflow or AUTO if you want the blower to operate only while the heat pump is operating.
Try to get the heat pump to turn on by raising the thermostat to its highest temperature setting.
If the air flow out of your registers seems low, check the air filter. An extremely dirty air filter can block air flow.
Make sure all registers are open and not obstructed.
Check the power disconnect switch by each unit (outdoor and indoor).
Check the fuse/breaker at the electrical panel for both the outdoor and indoor unit.