How to deal with a professor skipping his office hours?
Most faculty members state that they are available during their scheduled office hours or by appointment. If this is the case, then the most effective way for you to handle this situation is to send an email (or in-person) request for a short meeting outside of the regularly scheduled office hours.

If the request is declined, you may want to speak to the person in your department who is responsible for undergraduate education to let them know about the situation, and ask for help in resolving the situation.