Why are Muslims in disagreement with the book of Moses?

Was all scripture before Muhammed corrupt? Were they always corrupt? Why does the Qu'ran call these holy? When were they coruupted was this considered corrupt before Muhammed? Was it corrupted afer Muhammed? How did no other prophet of God not notice this corruption? How could Jews not notice when someone corrupted their scripture? Why didn't the Chrisitians notice the Jews scripture was corrupted and how come the Christinas have not noticed their scripture was corrupted? How does this make any sense to Muslims? Why can't they tell us this horrible time of all of these corruptions and why their prophet didnt notice and their scripture did not notice this horrible corruption did all of this happen after thousands of years of truth and not one believer noticed it?