Well, this could be interesting! First, if you have the CUSIP (the registration of the company) you might have an advantage. Assuming you have the stock certificate in order to get the cusip number. Turn the certificate over and you will find the “transfer agent” — the company that maintains stock registrations. They should be able to tell you the history of the stock, whether it went bankrupt or was purchased for shares in another company.
If all else fails there is a company called Stock Search International — that traces old stock certificates. But they charge a fee, or take a piece of the value if there is substantial value. Here is the link to their website. http://www.stocksearchintl.com/