Footage from Thor:Love and Thunder reveals that Mjolnir will be restored, but exactly how it will happens remains a mystery. While the Marvel Cinematic Universe had seemingly put Mjolnir to rest, it appears that that couldn’t have been further from the truth. Blue cracks in the hammer confirm that the weapon of Jane Foster's Mighty Thor is the exact same hammer once wielded by Hemsworth's character.
Thor: Ragnarok saw Mjolnir be destroyed by Hela to set up an arc for Thor to unlock his full potential as the God of Thunder. Avengers: Infinity War kept that going by giving Thor a brand new weapon, the Stormbreaker. 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.
Related: Thor: Love & Thunder Trailer All-But Confirms The Best Guardians Theory
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. One possibility is the simplest one available, which would hinge on the rules put on the hammer by Odin's enchantment, which are “Whoever holds this hammer, if he be worthy, shall possess the power of Thor.” Jane was able to take Thor’s place in the comics because she became worthy enough to wield Mjolnir, so if the enchantment is still in effect in spite of its destruction, then Jane’s worthiness might cause Mjolnir to reconstruct itself in order to serve as a weapon for a new master. Alternatively, Marvel can make Mjolnir's return to the MCU a bit more involved by having someone purposively rebuilt it. As for how who could pull that off, the MCU already has a character capable of accomplishing this feat. Here's how Thor: Love and
Read more on screenrant.com