>I use in an app the vfpskins product. I like it, use it, etc. But the developer has disappeared from the face of the earth. For over a year I have tried to find him via email, Google, forums, etc. No luck.
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>I need to make a change to the programming to get it to do what I need under terminal server. Can I throw my hands up in the air, decompile, and do it? What is the ethical approach to an abandoned product, and how long should I keep trying?

If the author did not provide source code, I can't see that it would ever be ethical to decompile, without his permission, until copyright is extinguished,

From a brief Google, the author appears to be Pablo Molina. It looks like he may be Argentinian. If you haven't tried already, one brute-force way might be to get the list of Argentinian UT members here, find those who have been active recently here and try e-mailing them. Maybe someone here who speaks Spanish (I don't) could help putting together an e-mail.