Thor's new weapon, Stormbreaker was implied to be even more powerful than Mjolnir, so that, coupled with Thor's character arc, made it appear that Mjolnir was gone for good. However, Thor: Love and Thunder is bringing it back and giving it to Jane Foster, who could wind up with it in one of a few ways.
Thor Odinson thought his old hammer Mjölnir had been lost forever. In Thor: Ragnarok, the God of Thunder (Chris Hemsworth) fought his evil sister Hela (Cate Blanchett) and lost—at least initially, anyway. In a devastating blow, Hela cracked Thor's mighty hammer into tiny bits.
In Love and Thunder, we learn that all the pieces of Mjölnir are kept in New Asgard, as a touristic attraction to those who wish to see the God of Thunder weapon.
It's gone. Destroyed By Hela. Once it is returned to its original timeline,it follows the same fate. Unless Captain America did something with it while journeying through the past,it will follow it's unfortunate path and will be destroyed exactly where it already happened in Thor Ragnarok.
Jane destroyed Mjolnir, but we see that it's been repaired by the end of the movie and is now being wielded by Thor's adopted daughter, Love. Sure, Thor seems to have moved on with his life and accepted that Jane was dead so that it wouldn't be an instant fix like in the comics.
The chemotherapy is attacking the cancerous cells but Mjolnir doesn't identify the cancer as an illness just as another part of her it needs to protect. Plus chemotherapy really does weaken Jane and make her sick so it's easy to see as an illness on it's own.
This led Jane to New Asgard, where the broken pieces of Mjolnir were held. Up until this point, no one had used Mjolnir — not even Thor, who likely believed that nothing could put the destroyed hammer back together. Jane's arrival in New Asgard woke up Mjolnir, allowing it to reform to transform Jane into Mighty Thor.
Why did Mjolnir choose Jane? The short answer is yes, Thor is still worthy of lifting Mjolnir after Thor: Love and Thunder. His worthiness comes down to the reason why Mjolnir chose Jane. In the comic books, Mjolnir does choose Jane to be Thor after Thor becomes unworthy and is unable to lift it.
Thanos didn't lift Mjolnir, Captain America did
With Mjolnir's worthiness enchantment resulted in Thor being able to lift the hammer only if he is considered to be worthy, but likewise, the enchantment is not discriminatory in nature, and anyone who is deemed worthy is able to lift the hammer.
Stormbreaker has the additional power to summon the Bifröst, allowing Thor to teleport anywhere in the Nine Realms. Screen Rant has identified Stormbreaker as the more powerful of the two, based on this ability, as well as it being a much larger and edged weapon.
Later in the film, a flashback to when Jane and Thor were still a couple shows exactly how she was able to wield Mjolnir. In a moment of wistful affection for his girlfriend, Thor asked his trusty hammer to always protect Jane, and in doing so unwittingly enchanted Mjolnir to do just that.
Gorr's Daughter Love is Chris Hemsworth's Real-Life Daughter
Jane Foster promises Gorr with her own dying breath that Thor will take care of the child, and Thor, now heartbroken and alone, chooses to adopt the child.
Appropriately, the young kid Love is played by Hemsworth's own daughter. Together the God of Thunder and his rambunctious adoptive daughter are set for more classic Thor adventures, which seems like a fitting send-off for Hemsworth as one of the last surviving heroes from the MCU original lineup.
Five years after the Snap, Thor time traveled to an alternate 2013 and brought its Mjølnir into the main universe's 2023, where it was used by Steve Rogers during the battle to fight an alternate Thanos. Afterwards, Rogers time-traveled to the alternate 2013 and returned Mjølnir.
Thor loses his eye during the earlier parts of the final battle sequence with this goddess. She casually and effortless beats him around the throne room, and then the moment happens. Hela strikes Thor across the face with her sword, literally slicing the eye from out his head right then and there. Brutal.
Eternity creates Love (India Hemsworth) and the father and daughter are reunited once more before Gorr dies. At the same time, Jane and Thor share one last laugh and one last kiss, before she turns to stardust in his arms — indicating that Mjölnir not only transformed her into Mighty Thor but into a god as well.
Mjolnir has been manipulated in different ways in Marvel Comics, and many years ago, Iron Man was able to hold the hammer… thanks to zero gravity, meaning that he didn't properly lift it and he would have still not been able to wield it on Earth because he wasn't worthy.
Every MCU fan remembers with excitement the moment in Avengers: Endgame when Captain America (Chris Evans) first lifted Mjolnir. This didn't come as a surprise to Marvel comic fans, since Cap has proved on multiple occasions to be worthy of the power of Thor.
In the case of Thor, all it took was a whisper of the simple phrase, “Gorr was right.” After hearing this, Thor was unable to wield Mjolnir. He was rendered unworthy, because in his heart he believed what Fury said was true.
Moon Knight even seized control of Mjolnir as he revealed that the Uru metal of the hammer is just another moon rock. So while Moon Knight couldn't physically wield the hammer, he could command it to obey his will. And that control extended to Khonshu as well.
Gorr planted seeds of doubt in Thor's mind, forcing him to question whether gods truly are as noble and benevolent as they seem. Nick Fury seizes on that doubt in 2014's Original Sin, telling Thor "Gorr was right" and rendering the god of thunder so disillusioned that he's no longer able to lift Mjolnir.
Jane does not transform into a god-like being like Thor himself. While she does get to wield his powers while in her Mighty Thor form, she is not permanently altered. Instead, she returns to her weakened human form once she lets go of the hammer.
The movie doesn't explain Thor's motivations for giving up Stormbreaker, but it makes sense that Chris Hemsworth simply wanted Love to have a powerful weapon to aid her in battle. It's unlikely that he could give her Mjolnir, considering that so few people in the MCU have been deemed worthy of its power.
Mysteriously, the broken pieces of Mjolnir, the hammer of the thunder god, transformed her into the Mighty Thor and gifted her the superpowers of Thor, to battle threats internal and external. Wielding Mjolnir herself, she had become a godly protector and a new hero was born!