New York Not since its local debut in the 1950-51 season has William Inge's ''Come Back, Little Sheba'' received a major New York production. The conscientious revival by the Roundabout Theatre Company of Inge's first Broadway play makes some amends for the neglect and also suggests why it has occurred. In 1984, the bleak drama about vanished dreams seems obvious and contrived. Yet it recalls the origins of a writer whose subsequent plays included the prize-winning ''Picnic,'' ''Bus Stop,'' and ''The Dark at the Top of the Stairs.'' Lola and Doc Delaney (Shirley Knight and Philip Bosco) occupy what became the familiar Inge fringe of middle-class, middle-American respectability. Doc, is a chiropractor who once dreamed of becoming a physician. A recovering alcoholic, he has remained dry for a year. Doc has learned patiently to endure wedlock with the slatternly Lola, an erstwhile high school beauty queen whom he married after she became pregnant with his child. Lola lost her baby and has been unable to bear further children. Doc concentrates on the present, on his practice, and his Alcoholics Anonymous commitments. Lola clings to the past, symbolized by little Sheba, the white puppy which has mysteriously disappeared. Lonely Lola sleeps late, neglects her housework, and passes the time of day making conversation with the postman, the milkman, and neighborly Mrs. Coffman. It remains for the Delaneys' pretty student boarder (Mia Dillon) to bring on the crisis that leads to Doc's sharp but temporary lapse from sobriety. In the aftermath of the ordeal, a somewhat chastened Lola realizes that little Sheba isn't coming back. A contrite Doc reavows his devotion to his pathetic wife. The Roundabout cast serves the text creditably under Paul Weidman's deliberate direction. The invaluable Mr. Bosco conveys all the pain and strain of a man living on the edge of desparation but determined to keep faith with a woman whose persistent immaturity is the only reminder of a bygone, innocent charm. Miss Knight's Lola is simultaneously exasperating and touchingly vulnerable. As the heedless undergraduate boarder whose hulking boyfriend stirs Doc to unnatural jealousy, Miss Dillon proves once more pertly tantalizing. — Play by William Inge. Starring Shirley Knight, Philip Bosco, Mia Dillon. Directed by Paul Weidner.