Has the quran ever been corrupted? im sure allah said the bible and torah was corrupted? and said he would?

and allah said he would never allow the quran to be changed or corrupted! the caliph uthman made his own version of the quran the official quran as confirmed in bukhari vol. 1book 56 #63. he then ordered that all other conflicting qurans be burned. so it is easy for non-muslims to see other versions of the quran existed during the time of uthman. so what happen that caused allah to allow corrupted qurans to exist. even today the western quran has hundreds of corruptions in it. so what are we to believe? so have there been different corrupted qurans or not?