The answer to 'dehumidifier not turning on' is that there can be several common causes, including a tripped circuit breaker, a faulty power cord or outlet, or an issue with the dehumidifier's internal components. If your dehumidifier isn't turning on, the first thing to check is the power supply - make sure the unit is plugged in securely and that the circuit breaker hasn't been tripped. You can also try plugging the dehumidifier into a different outlet to rule out an electrical issue.
If the power supply seems fine, the problem may be with the dehumidifier itself. Depending on the model, you may be able to troubleshoot and repair minor issues like a clogged air filter or a faulty control panel. However, if the issue is with the compressor or other internal components, it's best to call in a professional HVAC technician to diagnose and repair the problem.