Some password managers allow you to reset your password under some circumstances and some do not, so it will depend on what you use and how you’ve set this up. We recommend Bitwarden, with which you can recover your account if you lose your master password.
However, losing your master password is not the only way you can lose access to your password manager, however. If you have set up multi-factor authentication (MFA), which we highly recommend, and lose your second authentication factor (commonly your phone with an authenticator app), you can also lose access to your password manager. If you lose the ability to recover that MFA app through backup codes or a phone backup, this can also cause you to lose access to your password manager.
If you lose access to your password manager and can’t recover that access, you’ll have to reset all of your passwords to all of your online accounts that were stored in the password manager. If you have to go through the process of resetting your passwords, the key here is around the email or email addresses you used for each account. If you can access the email account you’ve used for an online service, you can use it to reset your password for that service. That is obviously an onerous process, but it may be the only way to recover your accounts should you lose access to your password manager. This also highlights the importance of protecting your email account(s), as it is the key to maintaining access to the service and potentially your password manager as well. We recommend that you keep the email account that may be associated with your password manager separate and not have those credentials stored in your password manager, for the purpose of compartmentalization should your password manager become compromised. When choosing a master password, we recommend that you choose a string of words that you can easily remember, but that can’t be easily guessed, with uppercase and lowercase letters, as well as a few numbers and symbols added in places that are memorable to you. Also as a reminder, we always recommend that your password manager and email accounts, among other important accounts and services, be protected with multi-factor authentication (MFA).