If the unit is not heating at all, check to see if the gas is turned on. Make certain the thermostat is on, the unit plugged in and the circuit breaker is on and was not tripped.
If the unit is not cooling, check the circuit breaker and thermostat.
If there is no airflow in your Trane heat pump unit, the air filters might be dirty. Clean or replace filters and see if this corrects your problem.
Another possible cause could be dirty coils freezing up. Turn off your thermostat for a few hours and see if the system unfreezes.
To head off problems, Trane recommends regular maintenance be performed each spring and fall to check the system and the ducts. The major components of the heating and cooling units should be checked out as well as the coils and blower housing.