Can I get a refund for unused train tickets?
If I can then how?

There's nothing about this on the www.RENFE.es website? No, maybe there's not. You might send them an email at venta-internet@renfe.es .

I could not find anything on the RENFE.es site. I have used the email address that you suggested and will wait for the reply.
Thank you, again MadridMan

This brings up a good question. Any idea what is happening at Charmatin? I was in there the other day they moved all the tracks around, ended up getting on the wrong train. As well they've removed most of the ticket machines and all the barriers to getting in. One can easily walk on the train without a ticket, but you still need a ticket to get out the other end.