My 35mm f2 canon lens's autofocus has stopped working. In manual focus mode the focus wheel is locked, and in autofocus mode the focus wheel spins freely but does not change the focus at all. In autofocus mode my camera recognizes when an object is out of focus and makes a single click noise, but the focus does not change.
Does anyone know what is wrong with the lens? I suspect it is the motor, but I cannot be sure. Is it possible/advisable to take it apart? I wouldn't mind taking it to a shop, but I want to avoid spending much money repairing the lens (50 dollars max).
edit: I bought it off ebay used, so I doubt it is under warranty.