Bip39 Passphrase. You would then do a standard recovery with a command such as just one beneath. (This command uses a sample wallet file bunlded with BTCRecover) This could include developing a direct backup, a cryptic hint that only you'd realize, sharing parts of the passphrase with trustworthy family members. https://sparxsocial.com/story9090946/ian-coleman-bip39-https-linktr-ee-bip39-the-fact-about-bip-39-that-no-one-is-suggesting