I've a Land Contract that has been defaulted on what is the legal procedures to follow

Depends on the terms of your contract, In all of the ones I ever used, I had a clause that said, once they went into default, the contract converted into a month to month rental. I would send them a notice that they were now under a rental agreement ( or offer to re-instate the contract for a fee)

So what happens if they are in default will depend on what terms for default you wrote into the contract.