When attempting to reset a tripped circuit breaker, always shut the handle to the off position before placing back to the on position. Not all circuit breakers will indicate whether or not they are tripped. In some cases you may want to shut off each circuit breaker and then back on again.
Periodic maintenance like having to re torque terminals and lugs inside your service panel or circuit breaker panel is recommended about every five years. Having loose wire connections to your circuit breakers can cause nuisance tripping and aid to the premature failure of equipment those circuit breakers serve such as your HVAC unit and appliances.