google gave me the link to some of the past prompts that ap has used:
AP: English Language
it's only prompts from 2002-2007, but it's better than nothing. my teacher has used some of them, too.
and don't freak out. look for a list of rhetorical devices on google or something, and try remembering what they are. remember things like periodic sentences, parallelism, interrupted sentences...whatever.
if your teacher has been total crap &didn't tell you alreadyy, know that there are 3 types of essays ap can give you: a synthesis question [like a dbq!], a rhetorical analysis question [so youu should know them!], or an argumentative [use your own experiences, etc. to argue something].