If your garage door opener has no power, but it is plugged in with the circuit breaker is ON, and you know FOR SURE the electrical outlet has power, then there is most likely something in the garage door opener that is faulty. If it is an electrical issue in the opener, you will need to check the internal components of your garage door opener with a multi-meter to find the source of the problem.
When dealing with electrical issues, it’s usually best to contact a local garage door expert and have an experienced professional look into the issue.