I'm running a somewhat modified version of the Lost Mine of Phandelver adventure.
I was DMing my second ever session, and decided to roll on the lingering injuries chart. I got a 3 and told the player, whose character was nearly killed by a group of orcs then and there, that they chopped off his leg and left him there. He made his death saves and stabilized, and another player character dragged him away to keep him safe.
I was not planning on the roll ending up being one to completely cut off his leg – but that's unimportant, as it's happened already, and I don't want to retcon it if I can help it.
I'm looking for a way he can regrow/regenerate his leg but I'm not sure how to go about it. It could be replaced with Regenerate but that is a 7th-level spell; I'm not sure how I should go about helping him to replace it, as the players are only 3rd level.
It's not important that the character necessarily recover immediately. I'm looking for options for how to go about this, as I'm new to all of this and want to do right.
In case it's relevant our party composition is a Variant (Winged) Tiefling Warlock of the Fiend and an Aarakocra Monk.
As far as I know, there are 2 basic ways to regrow a limb:
Alternatively, you could theoretically regrow a limb by dying, and then being brought back to life using any of the following spells:
However, as you outlined in your question, your party is at 3rd level, and these spells are beyond what could reasonably be cast by a 3rd level party. That being said, you're the DM - you can create a narrative hook to introduce some of these spells into your modified adventure.
For example, perhaps the party encounters a necromancer on their travels, who is willing to cast one of the above spells in return for some undertaking by the party (gold, slaying a monster, retrieving an item in the mines, etc). Or perhaps a member of your party has a patron god who is willing to lend their aid given the noble quest upon which the party has embarked.
Ultimately, as DM, you can build situations where the party will come across an entity capable of casting a spell which is of a higher level than the party can cast.