If have had a divorce and want to revert back to maiden name do I have to file petition with court?

No. Unless you legally changed your name to your married name, all you have to do is start using your maiden name. In Louisiana when you get married your name doesn't change, either spouse is simply allowed to use the name of the other spouse.

Bryan's answer is correct; however, if you want to change your driver's license, you will need something from the court. The DMV won't change your license without the social security administration changing your name, and social security requires a judgment (or a marriage license, if you were going in the other direction!).

Both attorneys are correct. In Louisiana, a woman always retains her maiden name. A woman's married name is adopted by custom, but her maiden name remains her legal name. As far as your passport is concerned, it may be easier to obtain a new passport in your maiden name than to try to change or explain the name change. Good luck.