1. The Book: Allah’s Quran
[Quran – 2:2] “This is the Book; in it is guidance sure, without doubt, to those who fear God;”

2. Allah Informed mankind about the need for Allah’s Guidance
[Quran – 2:213] “All Mankind were once one single community; [then they began to differ -] whereupon God raised up the prophets as heralds of glad tidings and as warners, and through them bestowed revelation from on high, setting forth the truth”

3. Allah Informed mankind about His Revelations to His Messengers
[Quran – 35:32] “Then (after every Messenger), We have made those of Our servants whom We chose heirs to the Book (to preserve and teach it, and secure its practice in daily life)”

4. Allah Informed mankind about some of the recipients of His Book
[Quran – 2:136] “Say: “We believe in God, and in that which has been bestowed from on high upon us, and that which has been bestowed upon Abraham and Ishmael and Isaac and Jacob and, their descendants, and that which has been vouchsafed to Moses and Jesus; and that which has been vouchsafed to all the [other] prophets by their Sustainer: we make no distinction between any of them. And it is unto Him that we surrender ourselves.”

5. Allah Granted Moses (PBUH), The Book
[Quran – 2:53] “And remember when We granted Moses (while he was on Mount Sinai for forty nights) the Book and the Criterion to distinguish between truth and falsehood, and the knowledge, and power of judgment to put it into effect, that you might be guided to truth and abide by it.”

6. Prophet Moses’s Book was Torah (Taurat)
[Quran – 5:44] “Truly, We caused the Torah to descend wherein is guidance and light. The Prophets give judgment with it, those who submitted to God, for those who became Jews and the rabbis and learned Jewish scholars who committed to memory the Book of God and they had been witnesses to it. So dread not humanity, but dread Me. And exchange not My signs for a little price. And whoever gives not judgment by what God caused to descend, those, they are the ones who are ungrateful.”

7. Allah Gifted David (PBUH) with Psalms (Zabur)
[Quran – 17:55] “And it is your Lord that knoweth best all beings that are in the heavens and on earth: We did bestow on some prophets more (and other) gifts than on others: and We gave to David (the gift of) the Psalms.”

8. Allah Gifted Jesus (PBUH) with Gospel (Bible)
[Quran – 5:46] “And We sent following in their footsteps, Jesus son of Mary, one who establishes as true what was before him in the Torah. And We gave him the Gospel in which is guidance and light, and that which establishes as true what was before him in the Torah and a guidance and admonishment for the ones who are Godfearing.”

9. Allah’s Continuation of Revelation
[Quran – 2:87] “For, indeed, We vouchsafed unto Moses the divine writ and caused apostle after apostle to follow him; and We vouchsafed unto Jesus, the son of Mary, all evidence of the truth, and strengthened him with holy inspiration.”

10. Allah Confirmed The Truth of Earlier Revelations
[Quran – 2:101] “For, indeed, We vouchsafed unto Moses the divine writ and caused apostle after apostle to follow him; and We vouchsafed unto Jesus, the son of Mary, all evidence of the truth, and strengthened him with holy inspiration.”

11. Allah’s Command to followers of Earlier Revelations to Believe in Quran
[Quran – 2:41] “Believe in what I have revealed in the Qur’an which confirms the Divine source of your own Scriptures. Do not be the first who reject Qur’anic revelations. Do not trade away my revelations for small profits and be at awe with none but Me.”

Also:
[Quran – 21:7] “O people of the Book, believe in what We have revealed, which confirms what is already with you before We disfigure your visages and turn your faces about and curse you, as We did with those who had broken the Sabbath; and what God decrees comes to pass.”

12. Allah Commanded The Prophet (PBUH) to Refer to Earlier Revelations
[Quran – 16:43] “And [even] before thy time, [O Muhammad,] We never sent [as Our apostles] any but [mortal] men, whom We inspired: and if you have not [yet] realized this, ask the followers of [earlier] revelation,”

Also:
[Quran – 21:7] “The messengers We sent before you were but men whom We had sent revelations. Ask the People of the Book if you do not know this”

13. Allah Confirms, Falsification, Alteration, Distortion in Earlier Revelations
[Quran – 5:13] “Then, for having broken their solemn pledge, We rejected them and caused their hearts to harden-[so that now] they distort the meaning of the [re-vealed] words, taking them out of their context; and they have forgotten much of what they had been told to bear in mind, and from all but a few of them thou wilt always experience treachery. But pardon them, and forbear: verily, God loves the doers of good.”

[Quran – 11:110] “And, indeed, [similar was the case when] We vouchsafed the divine writ unto Moses, and some of his people set their own views against it; and had it not been for a decree that had already gone forth from thy Sustainer, judgment would indeed have been passed on them [then and there]: for, behold, they were in grave doubt, amounting to suspicion, about him [who called them unto God].”

14. Allah Has informed mankind thus:
“whatever there still remains of earlier revelations!”

[Quran – 34:31] “And [yet,] those who are bent on denying the truth do say, “We shall never believe in this Qur’an, and neither in whatever there still remains of earlier revelations!”

See also:
[Quran – 2:97; 3:3; 5:48; 6:92; 10:37; 12:111; 34:31; 35:31]

Conclusion
[1] Earlier Revelations are not Extinct.
[2] Earlier Revelations are not available to us in Pristine form.
[3] Remnants of Earlier Revelations (“whatever there still remains of earlier revelations!”) are present in the Books of the followers of Earlier Revelations.