Currently, you cannot recover a forgotten master password. Zoho Vault is designed based on the Zero-Knowledge architecture. We never store or transmit any users' master password to our servers. Your master password is only known to you. If you can't remember your master password, you will have to reset it. This will result in the loss of your personal passwords. 

However, soon after you reset your password, we'll send an encrypted HTML file containing all your Zoho Vault data to your registered email address. If you happen to recollect the forgotten master password in the future, you can recover your passwords from this file. You can find more details in this article.