How do you unlock the personal vault?

Could you please elaborate on the process of unlocking a personal vault in the realm of cryptocurrency and finance? I'm particularly interested in understanding the steps involved, whether it involves a unique passphrase, a multi-factor authentication process, or perhaps a combination of both. Additionally, are there any security measures in place to ensure that only the rightful owner can access their vault, and what happens if the owner forgets their access details? I'm keen to gain a comprehensive understanding of this process.