Dear XXXXX Paspa:
I assume that since you are referring to 42,000 USD, you are either not in the United States, or if you are, you are from Europe but are talking about a debt the collector claims originated in the United States.
Unless there was a judgment entered against you in 1985 that has been renewed (and renewal of a judgment depends on where it was entered), this is improbable under most US law.
The statute of limitations for collecting on past-due debts runs, depending on the type of debt, from 2 years to 10 years. If the debt is reduced to judgment, the usual time for collecting on a judgment is seven years -- but the judgment can be renewed.
Your debt is probably subject to the Fair Debt Collection Practices Act. Under 15 U.S.C.S. 1692g, you are entitled to ask for validation debt. The collector needs to provide you with the following:
(1) the amount of the debt;
(2) the name of the creditor to whom the debt is owed;
(3) a statement that unless the consumer, within thirty days after receipt of the notice, disputes the validity of the debt, or any portion thereof, the debt will be assumed to be valid by the debt collector;
(4) a statement that if the consumer notifies the debt collector in writing within the thirty-day period that the debt, or any portion thereof, is disputed, the debt collector will obtain verification of the debt or a copy of a judgment against the consumer and a copy of such verification or judgment will be mailed to the consumer by the debt collector; and
(5) a statement that, upon the consumer's written request within the thirty-day period, the debt collector will provide the consumer with the name and address of the original creditor, if different from the current creditor.
Ask for this information immediately. If the collector cannot provide it, the debt is either invalid or not collectible.
If the collector does provide it, this is what you do:
If the consumer notifies the debt collector in writing within the thirty-day period described in subsection (a) that the debt, or any portion thereof, is disputed, or that the consumer requests the name and address of the original creditor, the debt collector shall cease collection of the debt, or any disputed portion thereof, until the debt collector obtains verification of the debt or any copy of a judgment, or the name and address of the original creditor, and a copy of such verification or judgment, or name and address of the original creditor, is mailed to the consumer by the debt collector. Collection activities and communications that do not otherwise violate this title may continue during the 30-day period referred to in subsection (a) unless the consumer has notified the debt collector in writing that the debt, or any portion of the debt, is disputed or that the consumer requests the name and address of the original creditor.
Any collection activities and communication during the 30-day period may not overshadow or be inconsistent with the disclosure of the consumer's right to dispute the debt or request the name and address of the original creditor.
This is a pamphlet by the FTC describing more about the Fair Debt Collection Practices Act: http://www.ftc.gov/bcp/edu/pubs/consumer/credit/cre27.pdf
By the way, if you end up making a payment on this debt -- even if you just do so because the collection agency scared you - it could be considered validating the debt, which would restart the time to collect on the debt.