Salem

I have locked myself out of my house by finding a mine shaft to a lower level and then being pummeled by about 20 bats at once. I can't get back into my house. If i simply rekey another lock will it replace the first lock? If this isn't possible, if I destroy my house will it blow up the containers inside as well?

if you don't have master key - you can't replace lock
if you destroy/salvage house - all furniture will be outside - but remember few furniture can't be return (lift) -> inside house (other house)
and many furniture decoy time in outisde...

Crafted furniture such as beds and chest will definitely remain when you destroy a house, as for other items (crafted or not) I don't know yet.

What Nsuidara is explaining above is: certain items will decay if not inside a house/building, and some of those items that decay cannot be lifted to be brought back inside a house.

You can equip a keyring to a dedicated slot on your characters equipment UI that holds 8 keys in total. This keyring(while equipped) will not drop/despawn on the ground when you KO and respawn.

That being said, you have to destroy the house and remake it, and be sure to not make the same mistake again of losing your keys like that because you kept them in a backpack or your inventory.

Always keep your keys on a keyring
Always keep your silver in a purse

Oh and make sure to put both the keyring and the purse in their assigned spots in your equipment screen - this will prevent both from being lost upon a knockout

Silver I did put in a purse, the keyring just ran out of metal to make one. Thanks so much everyone.

and, for future reference, while the keyring will prevent animals/random deaths from taking your keys, players will still be able to steal that keyring and any keys in them. Make sure to have spares somewhere (in other characters' keyrings)