For fun I made a movie from a script that was in a book. then I showed it to a friend and he loved it and then it just got around now I have people asking to buy it and saying I should send that to a film festival. now am I allowed to send it to film festivals as long as I said who the script was by? do I have to get written consent or what.

You defiantly have to get written consent. Technically you need the "rights" in order to make the film, otherwise it isn't your film to sell.

Contact the author in the book and ask how much it would cost for you to make his script into a film.

Tread carefully. You may just have to take what you learned from making this film and make a new film that you can legally make.

-Chris
Studentfilms.com

Ya that’s what I guessed at least I learned a lot from it
thanks
David

hey, try writing a letter to the author or publisher (or whoever owns the rights to the work you adapted) asking if you could adapt his/her work into a script. They'll probably say no, but it wouldn't hurt to try.