How do i eliminate cockroaches in my house?!?

Me and my family have lived in this apartment for 3 years and have never seen a big roach in it up until last week in my bathroom then my room yesterday by the kitchen door and today one fell from the bathroom fan it was so scary! Why the sudden outbreak!? We always keep the house clean because i somehow developed a phobia(huge fear) for the fat roaches PLEASE SOMEONE HELP!