Does the motor hum? If a humming sound is present but the blades do not turn, the gears are engaged but stalled. This is a high-torque situation; continued operation will burn out the motor. Is there silence? The thermal fuse may have tripped. The machine is effectively "dead" until it cools.
: Most shredders have a "Reverse" function. Running it in reverse for a few seconds can often back the paper out of the blades. paper shredder jammed