CHILD IN NEED

By GINIA BELLAFANTE

WINONA RYDER does not watch the news idly. When she tuned in two weeks ago and heard about a 12-year-old girl who was kidnapped by an intruder during a ! slumber party, the 22-year-old Age of Innocence star found herself becoming emotional. ''I put my hands over my face like, 'No, no, no, this can't be happening,' '' says Winona, struck by the fact that the missing girl was from her own quiet hometown of Petaluma, California. ''A crime against a child I just don't understand. I had to do something.'' Winona, who has wrapped up a new film, Reality Bites, did do something: she flew to Petaluma and offered a $200,000 reward for information leading to the child's return.