They want to start advertising again and said I'd have to take their ad.
Criminal Defense Attorney
I don't believe so. For the purpose of this answer, I'll presume that when you say discharged a debt to my company, you mean the debt was formally discharged in bankruptcy. You haven't said that. Technically, a debt is also discharged by paying it off.
If the debt was paid off, and you have a contract, whatever the contract calls for will control the question of whether you need to continue providing advertising space. If the debt was discharged in bankruptcy, then the contract was terminated, and you are released from any obligations under it. But, if the person just isn't paying under the contract, again, the contract terms will control.
Often the contract for such services is verbal, or established in some other way.