Thor: Ragnarok was a powerful storyline for the MCU's lovable Asgardian, Thor Odinson. As far as the character’s MCU journey goes, Ragnarok pushed Thor harder than ever before. During the movie, Thor saw the death of his father, the destruction of Asgard, lost an eye and even broke his trusty hammer Mjolnir.
In Avengers: Endgame, Mjolnir returned through time travel shenanigans so Steve Rogers could wield it against Thanos. However, at the end of the movie, Captain America took the hammer back to its place in the timeline. This means that, in the current timeline, the weapon is still broken.
Mjolnir will be reforged
In a recent leak, it was revealed that Jane Foster would be wielding Mjolnir alongside Odinson in battle. The image showed Foster and Odinson in their superhero costumes next to Valkyrie, a strong team for the upcoming movie.
In the image, Jane Foster appears to be clad in an outfit very similar to the original MCU Thor outfit. Furthermore, the new Mighty Thor is holding Mjolnir instead of the newly created weapon Stormbreaker.
From the image, it's hard to get any new details regarding the upcoming movie. However, zooming into the hammer shows that the weapon has been clearly repaired instead of making a new version. The image reveals that the hammer still has deep cracks from being destroyed by Hela.
Jane Foster needs the hammer
Thor: Ragnarok revealed that Thor Odinson doesn't need the hammer to be the God of Thunder. However, when it comes to Jane Foster, the inclusion of Mjolnir is essential to the character’s superpowers.
Much like the original versions of Thor in the comics, the powers of Thor are granted to Jane Foster through the hammer. Furthermore, if the movie follows the comics, Jane will be suffering from the effects of a deadly cancer.