Debts and Credit

In 1992, I made a purchase for $400. I didn't pay the whole debt off. In 1996 the company declared the debt noncollectable. The store I bought it from went out of business. I recently paid off a huge debt. I just received a collection notice about that debt from 1992. What was ironic is it is the same collection company I just made this large payoff to. I thought the debt declared "noncollectable" was long closed. This is the first time I have heard from them about that $400 debt. Is there a limitation on time and can a debt be reopened if declared "noncollectable, charged off"?

After a debt is charged off can the creditor try collecting from a person later?

If you have outstanding medical bills you have been paying, and the creditor has been accepting the payment for several months, can they turn around and send them(it) to collections?

I owe a local bank past due fees, and I obtained a loan from a loan company, they made the check payable to me, and just so happens the check was drawn on the bank where I owe these funds, I went through their drive up window and showed my ID to cash the check, They took the check and gave me a number to call and I did, but did not get an answer. I would like to know if a company without my permission just take a check made payable to me without my consent?

I was divorced 2 and a half years ago. In the divorce decree we were both responsible to pay half of any bad debt, or debt we owed together. I have paid my half, but because he has not paid his it is showing up on my credit report. How do I get it off my credit report? Because he has not paid it is stopping me from being able to get a home loan, what do I do?