Hello!
I have the following problem:
In my setting, magic has been around forever, it is one of the elemental forces of nature, but people didn't really knew how to properly use it until a certain event occurred 2385 years ago that enlightened people on it's use. This event is also the year 0 in the standard calendar. What event could have made this happen?
I was thinking maybe the discovery of some ancient scripts from a long lost civilization, but that's a bit of a cliché
I don't understand. If its an elemental force of nature, then it's something your people are long familiar with. Like the sun. The concept of harnessing the full power of the sun would appear magical and it's one of the "forces of nature." That isn't really an event that would go down as the event to set all calenders to 0.
Every calender is based on an expression of religion. Some calenders are set to the date of their born savior, while others are set to an event that marks the beginning of their religion. Going by that logic, then your event would have to be religious in tone.
If you want to go by the WoT (Wheel of Time), Robert Jordan marked the "Breaking of the World" as the event 0 that started his calender. But even that has some religious significance.