Jean Shepherd, nurse-maid to the night people, has returned to WOR radio after his astutely publicized sabatical of a few days. With two sponsors in hand he held forth until 1 o'clock yesterday morning, having begun his ne weekly stint at 9 P.M. Sunday. Mr. Shepherd was appropriately appreciative of the efforts of his post-meridian admirers in restoring him to the air waves, though he was hardly very generous in acknowledging the role played by the most ardent of day people, press agents. Anyway the master of stream-of-consciousness doubletalk is back, often amusing and often incredibly dull and sophmoric. * The best Shepherd is the one painting such a delightful image as 8,000 night people repairing to Jones Beach and forming a human pyramid; the police of the day world couldnot be expected to comprehend the relaxed smiles on the faces of the pyramiders. In such moments there is almost a Thurberish quality about Mr. Shepherd's off-beat musings; then he is a stimulating anecdote to the dreary world of cliche-riden conformity. But particularly in his new assignment - in early evening a listener's resistance is considerably higher than during the lonely hours of the dawn patrol - Mr. Shepherd needs too learn the gentle art of shutting up. He talks so much that he fritters awayhi effect; as they say in show business, he passes his blackout line. His is a wonderful suggestion. for example, that every crowd on a bus or a subway train contains the seed of iminent violence. But when he tries to detail what he has in mind, he only behaves like a disappointing day person. Mr. Shepherd's sponsors are an organization that provides instruction in foreign languages and, of course, that soap company which benefited from the allegedly unauthorized commercial delivered in its behalf. WOR's unpredictable philosopher tried earnestly to leaven the plugs with humor but before he gave up his whimsey was showing. A little Shepherd goes a long way.