Muhammad pbuh could not read or write but whenever he received Quran it was automatically memorized to Muhammad (PBUH) and became part of regular 5 times prayer. Lot of Muslims also memorized word by word. Muhammad (PBUH) when received dictated to some Muslims who were good writers; they wrote on animal skin etc. Every Ramadan angel Jibrael listened the Quran as recited by Muhammad (PBUH)!
In the last Ramadan Muhammad (PBUH) recited the entire Quran twice. In addition to writing on the animal skins there were many thousands of people who memorized entire Quran by heart. When in some battle lot of Huffaz got murdered people decided to put on paper as paper was recently invented in China; after all precautions 4 authentic copies of Quran were made and then copies of this Quran disseminated all over!
This Quran can be seen in millions of masajid. Visit a mosque near you and see yourself Quran! You can order a copy of Quran from Amazon and can download or can listen on you tube!
There is no two versions of Quran and hundreds of thousands memorize it by heart. Amazing children as young as 6 year old can memorize it! It is a living miracle as it froze its original Arabic language so Quran is as fresh today as was 1450 years back! No other language is frozen like that! Quran can be witnessed and seen everywhere in the world so it is a living miracle word by word from Allah in its original language! Translations are never equal to original! All wise people should must study Quran as it is the manual for their lives to succeed in both worlds!