Same problem - I deleted an e-mail from gmail

Hello,
I deleted a piece of e-mail from my g-mail account. From the "thank you" I just read, it seems possible. I just didn't see where it told that person the directions to do it. Could you give me directions on how to do it? It is just one day or two old and I actually have another from this person. I want to know this information for the future as well and realize that I could just ask this person to re-send the original e-mail.

Thank you for your time. him