The Internet Movie Database is a good place to find a listing of adaptations of your book into film, video or television. Try search the author's name or the name of the book. Realize that some adaptations of books have different names. For example Elmore Leonard's novel, "Rum Punch" was adapted into a Quentin Tarantino movie titled "Jackie Brown."
The Internate Movie database can also find reviews of those films. Look for the "Metacritic" and "other reviews."
Youtube and Vimeo may have adaptations.
Depending upon how old the adaptation is, it could be in the public domain. Here is a resource to find Public Domain Film, Video, and Television Shows Online.
There are also some archives of radio shows that may be adaptations of your book: Old Time Radio Archive.
Also try BBC's Novels Adapted into Radio Programs.
This book: American Broadcasting: A Source Book on the History of Radio and Television may be useful.
You can also find reviews of most movies and television shows in databases such as Academic Search Complete and the Readers Guide Retro (linked in the list below).
This historical New York Times newspaper provides genealogists, researchers and scholars with online, first-hand accounts and coverage of the politics, society and events of the time. Coverage is 1851 with 3-4 embargo. See Newspapers – U.S. Newsstream (Proquest) for current articles.
Dictionary of Media and Communication Studies, 9th Ed. by 
Contemporary Theatre, Film, and Television series