The Tirupati Balaji temple closed down for 12 years in 1800 due to a legend that a saint cursed the temple. The saint was angered by the actions of the then-ruler of the region, who had killed 12 innocent people. The curse stated that the temple would remain closed until the king had atoned for his sins.
Another legend says that the temple was closed because the head priest of the temple died, and his son was too young to take over his duties. The temple was closed until the son was old enough to be ordained as a priest.
There are also some historical records that suggest that the temple was closed due to financial difficulties. The temple had been heavily looted by invaders in the previous years, and the administration was struggling to make ends meet.
Whatever the reason, the closure of the Tirupati Balaji temple for 12 years was a major event in the religious history of India. The temple is one of the most sacred Hindu pilgrimage sites, and its closure was a great loss to devotees.
It is important to note that these are just legends and historical theories. There is no definitive answer to the question of why the Tirupati Balaji temple was closed for 12 years in 1800.