How or where would I look for stocks purchase 25 years ago... can't find certificates?

If you are sure that you originally had the actual stock certificates (as opposed to the stock being owned in "street name" as part of a brokerage account) then you can call the stock registrar and ask about getting replacement certificates. Most companies provide information on their web site regarding how to contact the stock registrar - look for a tab on the company's home page called "investors" or "shareholders" or something similar.