Looking for a past love I've not seen for 25 years.

Why?

I hope you don't except some great lost romance. You have changed, they have changed.
They may be married, with someone, or heck had a sex change operation, no one knows.

For finding, where did you know them from last? Where where they living, what were they doing? Do you know any of their family ?

Classmates.com, or Facebook.