What are the proofs about the fact that the Qur’an is protected and authentic? The short answer is…
The Qur’an is the last divine message that the Almighty Creator has sent down to all people who will come until the Day of Judgment. He (swt) did not only send down these supreme words, but also took it under His protection. This fact is explained in the Holy Qur’an as, “We have, without doubt, sent down the Message (i.e., Qur’an); and we will assuredly guard it (from corruption)” (Hijr, 15/9). This divine declaration is the greatest guarantee for Muslims about its protection. Indeed, history is the living witness to this. Because when the Holy Qur’an started to be revealed, it was both written down and memorized by Companions, constantly recited in prayers, and moreover, was reflected in their lives by being applied and manifested in the beliefs and deeds of Muslims. Following the demise of the Prophet Muhammad, the disorganized written pieces of the Qur’an were collected and a Mushaf was compiled in the period of Abu Bakr (ra).
Subsequently, with the increase in Islamic conquests and inclusion of new regions to the Muslim land in the period of the third caliph Uthman (ra), he convened a commission and the copies of Qur’an reproduced by this commission were sent to Mecca, Kufa, Basra, Damascus, Bahrain, and Yemen. Muslims prepared many copies of the Qur’an based on these first copies and this divine book has reached our era without any change. (For detailed information, see. “Mushaf”, DIA, XXXI, 242-248)
Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATWAS