I have a 91 accord ex. I just replaced the starter and ignition relay switch and still nothing. It's like the starter isn't engaging. What else could be wrong?

 

Is the battery fully charged ? Is the battery still good ? If you have an aftermarket alarm it's possible the ignition kill function of the alarm is malfunctioning. Those are a few possibilities off the top of my head.

This assumes obviously the car isn't cranking at all.

It's best to test for battery voltage at the small wire that connects to the starter when you crank the ignition to start. You should get battery voltage.