Its pretty much a cut and dry situation for returns on DVD, CD's and Video games...
A) Unopened you can return and get money back
B) Opened you can only exchange for the same title.
You may be able to talk to
Walmart Managers as stated. Usually the Cd's specifically say "clean" or "edited" on the side lable to denote the selection is free of any objective lyrics. I am not sure if walmart changed but I have bought several CD's there with objective language on them (most recent one being 2 weeks ago, SIMPLE PLAN's Latest)... Sometimes the clean versions just wreck the sound of the disk all-together (throw in a clean Eminem and see what you get

)
Definetly talk to a manage, they might work something out for you.
Seeing how Ashlee is the "punk" version of her sister Jessica, I use the word punk very loosely by the way, she could have some questionable lyrics... I just ran throug the lyrics on her CD "audiobiography" and this is all I could find:
Song: Autobiography
Lyric: I'm a bad *** girl in this messed up world
Lyric: You piss me off, good-bye
Ashlee has a hard voice to follow sometimes, could it be that she thinks she is swearing when she really isn't? Then again the songs could also be different from what the lyrics say aswell.
GOOD LUCK!