Wael Shihab, a Sharia researcher, said the Qur’an is perfectly preserved and kept. The Qur’an we have now is the perfect and complete Qur’an that was revealed to the Prophet (peace be on him).
No part, even a letter, is altered or taken out of the Qur’an. Allah Almighty has promised to keep it; Allah’s word is true and He fulfills His word.
Muslims keeps the Qur’an by heart, and they preserved it, further, in mus-hafs.