LastPass User Manual An easy to understand guide on how to use LastPass.

Reverting Your Master Password

On occasion, you may encounter an error when changing your master password caused by your browser during the reencryption process. There also may be times when immediately after changing your master password, you forget what you changed it to. LastPass creates an encrypted backup every time you change your master password. If it's been some time since you've changed your master password and you cannot access your account, you should try all the Account Recovery steps first to mitigate the chance of data loss. To access the revert feature, you must have access to the email registered to your LastPass account or, if you've set up a separate security email, access to that account. If you're concerned about the security ramifications of being able to revert a password change, you can disable the revert feature in your account settings.

The Revert Password Change Form

Navigate to the Revert Password Change page at https://lastpass.com/revert.php , and follow the instructions. Enter your LastPass email and submit the form. LastPass will email you within 15 minutes - inside the body of this email there is a time-sensitive link that must be accessed within two hours to work -- otherwise you'll have to restart the entire process. Once you've received the email, click the unique link inside, which will bring you to a page that allows you to choose the date to revert to:

Choosing the Date to Revert

Make sure to carefully choose the date to revert to, as any changes made since then will be lost - your entire vault will be overwritten with the backup data and your master password will change back. Once you've done this, try logging in again, with your previous Master Password.