There are several great examples of national spiritual revivals in the Old Testament. The best known and most important revivals were led by King Hezekiah and King Josiah.
King Hezekiah came to the throne in Jerusalem at age 25 (2 Chron 29:1) after the disastrous rule of his father Ahaz. On the first day of his reign (2 Chron 29:3,17) Hezekiah initiated a reform of the temple building and temple worship. In particular, he called the nation to celebrate the Passover (2 Chron 30). We are told that
So there was great joy in Jerusalem, for since the time of Solomon the son of David king of Israel there had been nothing like this in Jerusalem. (2 Chron 30:26)
King Josiah became king when he was eight years old (2 Kings 22:1), and ordered the repair of the temple in Jerusalem when he was 18 (2 Kings 22:3-7). During the repairs, the “book of the law” was discovered (2 Kings 22:8) — probably Deuteronomy — thus causing Josiah to learn of many areas where reform was needed. His reforms are described in 2 Kings 23 and 2 Chronicles 34-35, including a great Passover celebration, surpassing that of Hezekiah.
No Passover like it had been kept in Israel since the days of Samuel the prophet. None of the kings of Israel had kept such a Passover as was kept by Josiah, and the priests and the Levites, and all Judah and Israel who were present, and the inhabitants of Jerusalem. (2 Chronicles 35:18)