Safe and sure method - pull up the website for the state of New York, go to the area for Health and find the block for vital statistics. There would be a set of instructions on how to obtain a birth, death, or marriage certificate. Some states are strict on birth and death, but marriage certificates are public record and as long as you can provide bride and groom names, and a suspected date of the wedding, a certificate can be found or even created by the clerks office. Whether they will mail it or has to be an in person pick up is provided on the site.