I’m encouraged by you engaging with your friend about this. @RamiHalaseh has good points, I do believe as well that using the sources they trust in can help to your advantage in your dialogue with them, and I encourage you to do so. @SeanO has given a good video as well. You can learn a lot of things about Islam from David Wood’s ministry. He’s foundational in Nabeel Qureshi’s conversion.
Personally, I would just like to show you some quotes to answer your question on resources that may help you in your discussion with your friend, aside from those already given.
For Negative Apologetics:
 Grand Central Question:
"Commentaries from some of Islam’s earliest authorities provide little support for the idea that the Qur’an teaches that the biblical text (as opposed to the meaning) was corrupted. Gordon Nickel conducted a detailed study both of the Qur’anic verses Muslims use to support the idea of corruption and of the works of Islam’s earliest and most well-known commentators, Muqatil ibn Sulayman and Abu Ja’far ibn Jarir al-Tabari, to see whether they understood the Qur’an to say that the biblical text had been changed.
Nickel concludes that these seminal Muslim thinkers were very reluctant to read the Qur’an as accusing the Bible of having been textually changed. Rather, they interpreted the Qur’anic verses as charges against Jews and Christians who allegedly changed the meaning of the text to hide supposed prophecies about the coming of Muhammad and certain God-given laws that they did not want to apply. And even these alleged changes were done around Muhammad’s time in the seventh century, well after the New Testament canonization. At least one Muslim scholar agrees that the Qur’an doesn’t teach biblical corruption:
Contrary to the general Islamic view, the Qur’an does not accuse Jews and Christians of altering the text of their scriptures, but rather of altering the truth which those scriptures contain. The people do this by concealing some of the sacred texts, by misapplying their precepts, or by “altering words from their right position.” However, this refers more to interpretation than to actual addition or deletion of words from the sacred books.
Not only does the Qur’an call the Torah, the Psalms and the Gospel God’s word, but it also says in at least two places that “None can change God’s words” (Sura 6:115; 18:27). Islam’s most well-known commentator, Ibn Kathir, explains this verse:
Al-Bukhari [perhaps the most trusted early Islamic scholar], reports [that] Ibn ‘Abbas said that the [verse] means they alter and add although none among Allah’s creation can remove the Words of Allah from his Books. They alter and distort the apparent meanings. Wahb bin Munabih said, “The Tawrah and the Injil remain as Allah revealed them, and no letter in them was removed. However, the people misguide others by addition and false interpretation, relying on books that they wrote themselves. They say, “this is from Allah,” but it is not from Allah; as for Allah’s Books, they are still preserved and cannot be changed.
Every argument I had once used to convince Christians that the Bible had been corrupted was being dismantled one by one—by the very sources I relied on as a Muslim."
For Positive Apologetics:
 I Don’t Have Enough Faith to Be An Atheist
"How Accurate Is the Reconstruction?
In order to address the issue of accuracy, we need to clear up misunderstandings
many critics have concerning “errors” in the biblical manuscripts. Some have estimated there are about 200,000 errors in the New Testament manuscripts. First of all, these are not “errors” but variant readings, the vast majority of which are strictly grammatical (i.e., punctuation and spelling). Second, these readings are spread throughout nearly 5,700 manuscripts, so that a variant spelling of one letter of one word in one verse in 2,000 manuscripts is counted as 2,000 “errors.”
Textual scholars Westcott and Hort estimated that only one in sixty of these variants has significance. This would leave a text 98.33 percent pure. Philip Schaff calculated that, of the 150,000 variants known in his day, only 400 changed the meaning of the passage, only fifty were of real significance, and not even one affected “an article of faith or a precept
of duty which is not abundantly sustained by other and undoubted passages, or by the whole tenor of Scripture teaching.”
No other ancient book is so well authenticated. The great New Testament scholar and Princeton professor Bruce Metzger estimated that the Mahabharata of Hinduism is copied with only about 90 percent accuracy and Homer’s Iliad with about 95 percent. By comparison, he estimated the New Testament is about 99.5 percent accurate. Again, the 0.5 percent in question does not affect a single doctrine of the Christian faith."