And soon after my stepdad installed a cd player the power windows, gauges, int. wipers, and clock all quit working at the same time. What could it be? Is it a relay and if so which one and where?

Use a test light or multimeter to check for one or more blown fuses:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post252145