It follows from the texts of authentic ancient Islamic history that the Prophet (SA) had a number of scribes in Madinah. The scribes wrote the wahy, the Prophet's words, public contracts and transactions, the Prophet's agreements signed with pagans and with Ahl al-Kitab (the followers of the religions recognized by Islam to have existed earlier as true divine religions), the ledgers for sadaqat (charities) and taxes, the ledgers for war-spoils and for akhmas (plural of khums, an Islamic levy at the rate of one-fifth of one's savings and other items), and the numerous letters from the Prophet (SA) to various places.
In addition to the divine revelations and the Prophet's speeches, recorded, and remaining to this day, the agreements signed by the Prophet (SA) and most of the letters from the Prophet (SA) have been recorded in history. In his book: "Al-Tabaqat al-Kubra", Muhammad Ibn Sa'd quotes about one hundred letters, most of which he quotes in texts, from the Prophet (SA).
Some of these letters, addressed to the sultans and rulers throughout the world, to the chiefs of tribes, to the puppet Roman or Iranian rulers of the Persian Gulf, and to other persons, are invitations to accept the faith of Islam. Some other letters consist of circulars and procedures, which comprise fiqh (Islamic jurisprudence). Other letters serve different purposes. A good many of such letters expose their writers, as the scribes indicated their names at the bottom of the letters. It is said that the one who initiated the traditional practice of having the scribe's name entered at the bottom of a letter was Ubay ibn Ka'b, a known companion of the Prophet (SA).
None of these letters, agreements or books has ever been written in the Prophet's handwriting; that is to say, nowhere has it been reported that the Prophet wrote by his own hand. More important still, is the fact that there is no observed instance to indicate that the Prophet had written down a single verse of the Qur'an. At a time when each and every scribe of the wahy, wrote in the very Qur'anic style, would it be possible that the Prophet (SA) should write, but not in the Qur'anic style, or that he would not write a surah (chapter), or at least a verse, of the Qur'an?
In the books of history the names of the Prophet's scribes have been recorded. Al-Ya'qubi, in volume 2 of his historical work, reports:
"The Prophet's scribes, who wrote the wahy, letters, and agreements are `Ali ibn Abi Talib, `Uthman ibn `Affan, `Amr ibn Al-`As, Mu'awiyah ibn Abi Sufyan, Shurahbil ibn Hasanah, `Abdullah ibn Sa'd ibn Abi Sarh, Al-Mughirah ibn Shu'bah, Ma'adh ibn Jabal, Zayd ibn Thabit, Hanzalah ibn Al-Rabi`, Ubay ibn Ka'b, Juhaym ibn Al-Salt, Husayn Al-Numayri." 
In `Al-Tanbih wal-Ishraf", Al-Mas'udi describes in some detail, the nature of the task undertaken by the scribes, and indicates that they had a more developed sort of activity coupled with a kind of order, organization and work allocation among themselves. He reports:
"Khalid ibn Said ibn Al-`As was at the Prophet's service. He recorded the various needs which came up, and so did Al-Mughirah ibn Shu'bah and Husayn ibn Al-Numayr. `Abdullah ibn Arqam and Al-`Ala' ibn `Uqbah recorded documents, contracts and transactions for the public. Al-Zubayr ibn Al-`Awwam and Juhaym ibn al-Salt wrote down taxes and sadaqat. Hudhayfah ibn Al-Yaman was in-charge of entering the receipts (hirazah) of Hijaz, Mu'ayib ibn Abi Fatimah Dusi recorded war-spoils. Zayd ibn Thabit al-Ansari wrote letters to rulers and kings whilst serving as a translator to the Prophet. He translated Persian, Roman, Coptic and Ethiopian languages, all of which he had learned from those who knew these languages, in Madinah.  Hanzalah ibn Al-Rabi` was a relief recorder who would take over the function of any one of the above-mentioned people who failed to attend. He had come to be known as: "Hanzalah al-Katib (the writer)". During `Umar's Khilafah when Muslims had earned victories, Hanzalah went to "Raha", where he died. `Abdullah ibn Sa'd ibn Abi Sarh served as a scribe for a time, but later he lost faith and joined the pagans. Shurahbil ibn Hasanah Tabikhi also wrote for the Prophet and Aban ibn Sa'id and Al-`Ala' ibn Al-Hadrami also occasionally wrote for the Prophet. Mu'awiyah too wrote for the Prophet but only for a few months until the Prophet's death. These were the people who served as official scribes to the Prophet. However, we will not mention the names of those who have written a letter or two and who are not named among the Prophet's scribes." 
In this connection, Al-Mas'udi has made no mention of the "Book of Revelations" nor of the scribes of official documents; among them `Ali (AS), `Abdullah ibn Mas'ud and Ubay ibn Ka'b, etc. He seems to have meant naming those who held a title other than that of recording the wahy.
In the histories and ahadith of Islam, we come across a good many stories of the visiting enthusiasts from far and wide who sought, the Prophet's advice and to hear his preaching, the Prophet (SA) would respond with wise and meaningful words, recorded either concurrently or subsequently.
Here too, we find no instance of the Prophet (SA) himself writing a single word in response to the visiting enthusiasts. Obviously enough, if only one line written by the Prophet (SA) could have been found, it would have been preserved by the Muslims as a blessing and great honour for themselves and their families. Yet, in the case of Hadrat Amir al-Mu'minin, 'Ali (AS) and the other Imams (AS), we see many instances, where part of their manuscripts have been preserved in their own, or in their Shi`ah (friends) families. Nowadays, there are copies of the Qur'an, which had been written by these great personalities.
The story's widely known of Zayd ibn `Ali ibn Al-Husayn (AS), and that how they preserved "Al-Sahifah al-Sajjadiyyah", is a proof of this proposition.
Relating an interesting story in the first part of the second chapter, of his book: "Al-Fihrist" Ibn al-Nadim relates:
"I became acquainted with a Shi'ah of Kufah whose name was Muhammad ibn Al-Husayn nicknamed Ibn Abi Ba'rah. He owned a library the like of which I had not seen. He had taken over a library from a Shi'ah of Kufah. The strange thing was the fact that each book or each sheet of the book indicated the name of its scribe. A host of scholars had verified in writing the scribe's name. At that library were kept manuscripts of the two Imams, viz, Imam Al-Hasan ibn `Ali (AS) and Al-Husayn ibn 'Ali (AS). Also kept at the same place were documents and agreements written by `Ali (AS) and by other scribes of the Prophet (SA)."' 
It is true, that they have thus taken care of the blessed works. How could it be true therefore, that the Prophet (SA) should have written one line and that that very line should fail to remain, keeping in view the unbelievable regard which Muslims had for the protection of works, sacred ones in particular?
By analyzing the available evidence the question of the Prophet (SA) having written, (even during the period of his prophethood) is out of the question, even if there is a little evidence to indicate that he could read at this time. Rather, the greater portion of the available evidence testifies to his having not read, even in this period.
. Al-Ya'qubi, Tarikh al-Ya'qubi vol 2, p 69.
. In the book: Jami' al-Tirmidhi Al-Tirmidhi narrates from Zayd ibn Thabit that he said: "The Holy Prophet (SA) of Islam commanded me to learn the Syriac language. Also Al-Tirmidhi narrates in Jami' al-Tirmidhi from Zayd ibn Thabit that he said: "The Holy Prophet (SA) of Islam commanded me to learn the language of the Jews and said: "I swear by Allah that I cannot trust the Jews for my letters." I learned for about one-half of a month. After that whenever he (the Holy Prophet (SA) of Islam) wanted to write a letter to the Jews, I wrote it and whenever he received a letter from the Jews, I read it for him." In Futuhal-Buldan Al-Baladhuri, says on p. 460: "Zayd ibn Thabit said: 'The Holy Prophet (SA) of Islam commanded me to learn the Book of the Jews (in the Syriac language). Zayd ibn Thabit also said that the Prophet (SA) told me 'I am worried about my Book because of the Jews.' Scarcely had one-half of a month or a year passed that I learned it. From then on, I wrote his letters to the Jews and also read to him (to the Holy Prophet (SA) of Islam) the letters the Jews wrote to him."
. Al-Mas'udi, Al-Tanbih wal-Ishraf, p 245-246.
. Ibn al-Nadim, Al-Fihrist, Al-'Istiqamah Press, Cairo, p 67.