All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
There is no contradiction between the verses at all, praise be to Allah. Rather, they all indicate the same meaning, which is that the wind destroyed all that it was commanded to destroy. Verse 51:42 {It left nothing of what it came upon but that it made it like disintegrated ruins.} means that it turned everything that it was commanded to destroy into dust and ashes, as it did not destroy Hood (Hud), may Allah exalt his mention, and his followers, nor did it destroy their houses, as stated in another verse. As for verse 69:8 {Then do you see of them any remains?}, it does not pose any problem to begin with, as the verse refers to the destruction of the people who disbelieved in Hood (and not their houses).
Al-Maatureedi wrote:
“This wind spared nothing that it was commanded to reach and authorized to destroy but that it reduced it to ruin. Do you not see that it came upon things that it did not destroy. Prophet Hood, may Allah exalt his mention, and his believing followers were safe from it. When they (people of Hood) saw it at a distance, they thought that it was a cloud bearing rain, as in the verse: {And when they saw it as a cloud approaching their valleys, they said: This is a cloud bringing us rain!} [Quran 46:24] Hood, may Allah exalt his mention, replied: {...Rather, it is that for which you were impatient: a wind, within it a painful punishment.} [Quran 46:24] Another verse reads: {Destroying everything by command of its Lord. And they became so that nothing was seen (of them) except their dwellings.} [Quran 46:25] Allah, The Exalted, clearly stated that the wind spared their houses. It destroyed all that which it was commanded to destroy so that we know that it worked at the command of Allah, The Almighty.”
Ibn Katheer, may Allah be pleased with him, wrote, “It destroyed everything of their land by the command of Allah and reduced it to disintegrated ruins. [Quran 51:42] {And they became so that nothing was seen (of them) except their dwellings. Thus do We recompense the criminal people.} [Quran 46:25] It means that they were all destroyed and none of them (the disbelievers) remained alive, and that this is Allah's Judgment regarding those who reject His Messengers and disobey His commands.” [Tafseer Ibn Katheer]
Allah knows best.