“ We have, without doubt, sent down the Message [the Qur’an]; and we will assuredly guard it [from corruption] ”. (Al-Hijr 15:9)
From today 14 centuries have past and the Holy Quran is untouched and it has maintained its purity form exactly as it was revealed to Prophet Muhammad (pbuh)
The oldest copy of Quran is yet preserved, one is in the city of Tashkent, (Uzbekistan) and the second one is in Istanbul (Turkey).
You can have a view of Oldest copied of Quran preserved in Turkey, Click on the link below
This promise from Allah Almighty to protect the Qur’an is very important for us as Muslims in order to have confidence in the source of all our knowledge about Islam, the Qur’an. As you know, people before Islam had received messages from Allah (many, some of those were the Torah, the sabur, and the Injeel), which they eventually corrupted with changes, additions, and deletions.
The difference between Islam and the religions before Islam, including heavenly religions, is in who was assigned with the protection of the message. In Islam, Allah entrusted Himself with the protection of the Qur’an; whereas, before, only humans were entrusted to the protection of the divine Scriptures and Humans changes it for their benefits.
The Qur’an says what means:
“ It was We who revealed the law [to Moses]: therein was guidance and light. By its standard have been judged the Jews, by the prophets who bowed [as in Islam] to Allah's will, by the rabbis and the doctors of law: for to them was entrusted the protection of Allah's book, and they were witnesses thereto: therefore fear not men, but fear Me, and sell not My signs for a miserable price. If any do fail to judge by [the light of] what Allah hath revealed, they are [no better than] unbelievers. “ (Al-Ma’idah 5:44)
So Allah is the Trustee of the Qur’an, He is protecting it from any corruptions