Allah has sent down his revelations for guidance of the mankind to different Messengers in the form of Holy Divine Books.
And We certainly sent into every nation a messenger, [saying], "Worship Allah and avoid Taghut." And among them were those whom Allah guided, and among them were those upon whom error was [deservedly] decreed. So proceed through the earth and observe how was the end of the deniers. (Quran 16:36)
Some of them mentioned in the Quran many messengers were not mentioned
Some messengers We have already told you about, while some messengers We have not told you about. And Allah spoke to Moses directly(Quran 4:164)
However every book except Quran were partially changed by their followers & also are not preserved in their original forms.
And believe in what I have sent down confirming that which is [already] with you, and be not the first to disbelieve in it. And do not exchange My signs for a small price, and fear [only] Me.