How were wormholes discovered?
Wormholes have never been discovered.
The concept of a wormhole as a bridge between two points in space is mainly science fiction.
General Relativity does allow wormholes in the form of an Einstein-Rosen bridge. The problem with this is that for anything to pass through it requires an exotic negative energy matter which has effectively negative mass. This has never been observed and probably doesn't exist.
So, wormholes have never been observed. They are theoretically possible, but require new physics to detect and possibly utilise them.
For now, wormholes probably don't exist. They most certainly have never been discovered.