Sounds like a barrel tab broke, only way to fix is ordering a new lens unit, off e-bay. Usually after a lens unit, and a top cover needed for this camera... you will prolly save money just buying a new camera.
unfortunate part of plastic point and shoots... If you want a really good Canon point and shoot series check out the G series... I believe they are on the G12 now, even the old G9 is a good one though.