Albert Barnes Commentary Lamentations 2:9

"Her gates are sunk into the ground; he hath destroyed and broken her bars: Her king and her princes are among the nations where the law is not; Yea, her prophets find no vision from Jehovah." — Lamentations 2:9 (ASV)

Her gates are sunk into the ground - So completely destroyed, that one might suppose they had been swallowed up in an abyss.

Her king - The prophet’s lamentation, which before was chiefly occupied with the buildings of the city and temple, now turns to the people, beginning with their temporal rulers.

The law is no more - The Jewish Law, the Torah, came to an end when it no longer had a local habitation. Its enactments were essentially those not of a universal religion, but of a national religion, and the restoration of the nation with a material temple was indispensable to its continued existence. It was only when elevated to be a universal religion, by being made spiritual, that it could do without ark, temple, and a separate people.

Her prophets also find ... - With the Torah, the special gift of prophecy also ceased, since both were unique to the theocracy; but it was not until the establishment of Christianity that they were finally merged in higher developments of grace.