The answer to 'duct cleaning not heating' is that duct cleaning alone is unlikely to resolve issues with your heating system not working properly. Duct cleaning is primarily for improving indoor air quality, not fixing heating problems.
Some common causes for a heating system not working after duct cleaning could be a problem with the furnace itself, such as a faulty thermostat, pilot light issue, or other mechanical failure. Duct blockages or damage could also restrict airflow and prevent proper heating. In most cases, you'll need to have a professional HVAC technician inspect and diagnose the root cause of the heating problem.