Torah or Tawrat was revealed by Allah to His Prophet Musa (Peace be upon him), to be a source of legislation for the Jews of the 'Children of Israel'.  Presently the first 5 chapters/books (Pentateuch - Genesis, Exodus, Leviticus, Numbers, Deuteronomy) of the Old Testament are considered to be revealed on Prophet Musa (AS). The other books that were revealed by Allah are the Quran, the Zabur, the Injeel (Gospel), and the Scriptures of Ibrahim and Musa (Peace be upon them). 
He has sent down upon you, [O Muhammad], the Book in truth, confirming what was before it. And He revealed the Torah and the Gospel. Quran Surah Al’e Imran 3:3
Verily, We did send down the Taurat (Torah) [to Musa (Moses)], therein was guidance and light, by which the Prophets, who submitted themselves to Allah's Will, judged the Jews. And the rabbis and the priests [too judged the Jews by the Taurat (Torah) after those Prophets] for to them was entrusted the protection of Allah's Book, and they were witnesses thereto. Therefore fear not men but fear Me (O Jews) and sell not My Verses for a miserable price. And whosoever does not judge by what Allah has revealed, such are the Kafirun (i.e. disbelievers - of a lesser degree as they do not act on Allah's Laws). Quran Surah Maidah 5:44 [a]
The Prophet Musa (Pbuh), received the Torah from Allaah, the Almighty, on Mount Tur in Sinai. Musa, may Allaah exalt his mention, wrote it down with his own hands. Later, he ordered that this version should be put in the Ark of the Covenant. This version of the Torah was lost and in 600 B.C. a Jewish monk claimed he had found it. However, this version was also lost when Nebuchadnezzar destroyed Jerusalem. This indicated the advent of the "Old Testament" when a group of Jewish monks attempted to re-written the Torah, but there were many distortions and falsifications to the original and the truth was mixed with falsehood. This all was stated in The Old Testament that is used nowadays by the Jews and the Christians. 
Do you covet [the hope, O believers], that they would believe for you while a party of them used to hear the words of Allah and then distort the Torah after they had understood it while they were knowing? Quran Surah Baqrah 2:75
Qutaadah said: “The phrase ‘then they used to change it knowingly after they understood it’ refers to the Jews, who used to hear the words of Allaah, then they altered it after they had understood what it meant.”
Abu ‘Aaliyah said: “They took what Allaah had revealed in their Book describing Muhammad (peace and blessings of Allaah be upon him), and changed its meaning.” Ibn Zayd said: “The phrase ‘[they] used to hear the Word of Allaah (the Tawraat), then they used to change it’ refers to the Tawraat which Allaah revealed to them; they changed it, making what it permitted forbidden, and what was forbidden allowed, changing the truth to falsehood and falsehood to truth…” [Tafseer Ibn Katheer] 
Changing Omitting Adding things and attributing to Allaah words that He did not say, Misinterpreting the words of Allaah.
When Muhammadﷺwas sent, the original Tawraat and Injeel had already been altered and distorted. Allaah revealed the Qur’aan to His Prophet Muhammadﷺ, and guaranteed that He Himself would preserve it, as He says (interpretation of the meaning): “Verily We: it is We Who have sent down the Dhikr (i.e., the Qur’aan) and surely, We will guard it (from corruption).” Quran Surah al-Hijr 15:9
This distinguishing feature was not found in any Book before the Qur’aan. From the time of Muhammadﷺuntil the present (more than fourteen hundred years) the Qur’aan has stayed the same, and not a single letter of it has been changed, as ancient manuscripts and the hearts of generation after generation of people who have memorized the entire text and earned the title of “haafiz” bear witness. May Allaah guide us to the true and straight path. 
The Muslim individual believes that these books were revealed by Allaah The Almighty. They called to At-Tawheed (monotheism) and to associating nothing with Him. Allaah The Almighty Says (what means): And We certainly sent into every nation a messenger, [saying], "Worship Allaah and avoid Taghooth. Quran Surah Nahl 16: 36
The Muslim believes that the wisdom behind revealing books is to guide human beings to the straight path of Allaah The Almighty, eliminate disagreement and discord from among them, bear for them the glad tidings of the pleasure of Allaah The Almighty if they obeyed Him and warn them against His punishment if the disobeyed Him; and that the heavenly books – other than the Noble Quran – have not remained in their original state in which Allaah The Almighty sent them down; rather, they were exposed to alteration and distortion and the words of humans have mingled with the Words of Allaah The Almighty in them. 
A Muslim must believe in all the Heavenly Books and he must believe that they are from Allah. It is not lawful for him to abide by its laws, since these Books were revealed to certain nations at certain times.  So Quran is the final book for entire mankind which is to be followed. Allah said: “Verily, We have sent down to you (O Muhammad) the Book for mankind in truth. So whosoever accepts the guidance, it is only for his own self; and whosoever goes astray, he goes astray only for his own loss.”Qur’an Surah Zumar 39:41
And Allaah knows best.