Disconnect the power to the range for 1-2 seconds and reconnect it. This will cause the electronic range control (clock) to reset itself.
Press cancel and see if the door unlocks.
If this doesn't work, try to set the range into the "clean" cycle for 30 minutes. Let the range heat for 5-10 minutes and cancel the clean cycle.
If the door still doesn't unlock, the door lock assembly will have to be removed from the range and the motor and micro-switch tested with a volt/ohm meter. This is best done by a technician.
If this is the case, I recommend you go to
and get a Sears technician to repair the range.