""Yahweh, Your word is settled in heaven forever."" - Psalm 119:89
"The grass withers, the flower fades; but the word of our God stands forever." - Isaiah 40:8
"All Scripture is God-breathed and is valuable for teaching, for reproving, for correcting, for training in righteousness, so that the man of God may be fully competent, thoroughly equipped for every good work." - 2 Timothy 3:16,17
God has preserved His Word. Men have tried to change it and distort it, but God has always preserved it, for it is the means by which all men might know Him and be saved. The Old Testament Hebrew Text was written by 32 holy men of God over a span of around 1600 years, and almost all scholars who take the Bible literally accept that the Masoretic Text is the preserved original text, especially since the Dead Sea Scrolls were found in the Qumran Caves in 1947. (In Biblical numerology, 32 is a covenant number.) The New Testament Greek Text was written by eight holy men of God over a span of around 50 years, and it is the number of ancient copies is the largest of any book. (In Biblical numerology, eight is a number of new beginnings, and 32+8=40 is a number that associated with being tried and tested.)
Sadly, the devil has tried since the days of Adam and Eve to discredit God's Word and corrupt it (see Genesis 3), so he has similarly introduced corrupted versions of the Greek New Testament in order to corrupt the Word of God today. In fact, most modern Bible translations are based on a corrupted text! This doesn't mean that it's worthless. It's just like eating GMO food - it doesn't provide the same nourishment for the soul as the original Greek text and translations derived from the original Greek text. Scholars call the original text the Majority Greek Text (M-Text), because the majority of the available texts are quite similar. A small minority (that has become popular in most seminaries) is called the Westcott-Hort (W-H Text) / Nestle Text.
Below is some information to get up to speed on the topic.
Dr. Wilbur Pickering has been a Greek scholar for decades. He has written a book called, The Identity of the New Testament Text, in which he explains the errors of the Westcott-Hort critical theory and why the Majority Text is superior. See also What Difference Does It Make?. He also has dedicated much of his life to providing the Greek New Testament in a form that is as close to the original manuscripts. This is called the New Majority Greek Text. It is similar to the Robinson-Piermont and the Byzantine Majority Greek Text, but it is believed by many to have been better collated. He has also written his own New English Translation, which is based on his New Majority Greek Text. He has kindly made these available for free to all on his website (Mt. 10:8).