Classes have resumed at Central Connecticut State University, and counseling is being offered a day after a student dressed in what was apparently a Halloween costume with a mask and sword prompted a three-hour campus lockdown and a massive police response. No one was harmed. Officials said campus life was returning to normal Tuesday. The student — David Kyem, 21, of Newington — was charged with breach of peace, and he posted bail Monday. He did not return a phone message Tuesday. His father, a geography professor at the university, said his son caused the commotion while returning to his dormitory in a costume, after attending a party at the University of Connecticut.