What does the Quran say about the previous books? Were these books textually corrupted or were they available in an intact form at the time of the revelation of the Quran?
The following Quranic verse may indicate that they were indeed available intact:
[5:47] And the people of the Injeel shall rule in accordance with what God has brought down therein. Those who do not rule by what God has brought down are the wicked.