I am assuming you cannot find this information out from your family or you would not be asking the question here. If there is real estate involved then your best bet would be to search in the register of deeds office to see who bought the real estate. If there is no real estate involved then it becomes a bit more complicated and some facts may prove impossible to find, especially if the business was sold in pices rather than as a going concern. I would suggest you use the find a lawyer tab above to locate an attorney in your area. There are several attorneys who offer free initial consultations who will explain all the places you would need to go to gather the information. You can always try the local news or chamber of commerce as well if it is a small town. Good Luck.
Nothing herein is intended to create an attorney client relationship and the response is intended to provide generally a broad response to the area posed by the question. Each question is governed by unique facts and no answer provided is intended to specifically answer the question, but is a general overview of the area of law contained in the question.