Hi, probably sheared the roll pin off the end of the engagement lever, item #4 in the photo below.
The PTO lever can be removed as others have said and replace the roll pin in item #4, then it will take some maneuvering of the lever when re-installing to get the roll pin back into the groove in the collar in item #5. It is a very simple engagement mechanism where the collar is pushed by the PTO lever to connect the PTO front shaft to the PTO rear shaft.
This problem usually happens when the PTO clutch gets out of adjustment or seizes to the flywheel and the Operator tries to force the PTO into gear.
For more complicated PTO problems see the B414 PTO link below.