Research the location where the speech was given. Many places have their own websites, and those that host public speakers frequently may keep records of them. Type the name of the location into your search engine and check its website. If the website does not contain the information you need, it may provide contact information so you can email or call for further help.
Look up the speaker herself. Professional speakers often have their own websites. Type the speaker's full name into the search engine. If she has a website, it may include copies of her speeches. Speeches may be organized by topic, date or location, and they may be archived in a separate section of the website.
Visit your local library or bookstore. Look up books or articles within periodicals that the speaker has had published. Odds are, you will be able to access all the speaker's published works either via the internet or in print. Some bookstores or libraries might not have all the works on hand but will most likely be able to order them for you.
Contact the speaker's representative. This information is most often found in the back of a published work or on the speaker's personal website. The representative's information should be easy to find, because this is how public speakers are booked for appearances. A representative will be able to tell you whether the speech you are looking for has been, or will be, published.