What file initiates blu-ray playback?

After copying a blu-ray disc with AnyDVD, I can’t seem to find the exact file that initiates the playback of the disc and gives you access to the menu options. If I could find that file and open the disc from there, then if I had a problem with automatic downshifting to the French language tract, I would think that I could change the language back to an English tract. Does anyone know what is the initiating file on a blu-ray disc that is first read by a blu-ray player?