How long? Since 1962 or 1789?
If you don’t know when it was lost, how would you know when, and if, “it” was discovered?
It’s meaning (the Gospel of Jesus) during the years just following VC II.
It took the prayers and hard work of both Blessed JP II and Pope B-E, and now add in Pope Francis to bring the good news of the Gospel of Jesus back to the forefront.