In case you cannot remember or find the credentials you use to login to an account, here is some advice you can try out:

Recovery account - Most platforms and online service providers offer an option to set up a recovery or backup contact, usually an email address, a phone number, or a set of one-time backup codes. It is very important to set up this option so you don’t get locked out of your account. Regularly check that you still have access to your sign-up account and protect your recovery contacts just as you protect your main account, especially if you belong to an at-risk group.

In case you can’t access your account and you are not logged in on any other device, use your backup email address or phone to gain access to the original account. Make sure you have access to your backup communication method/account - otherwise, you might never be able to access the lost account - and check this regularly. It is important to secure the backup account as well, because it could grant someone full access to the main account.

Google provides an option to set up a recovery email account and phone number within the Personal info section of your Google Account. For Yahoo, you can use the Account Security page to add a recovery method, i.e. a phone number or an email address. Outlook, Hotmail, and other Microsoft accounts can also add a recovery email in the account security section.

Check the browser for saved passwords - Modern browsers (Firefox, Chrome, Edge) have the option to save your passwords, so you don’t have to enter them every time you log in. However, it is more secure to use a separate password management software such as KeePass, KeePassXC, or Bitwarden.

In cases where you cannot log in by typing your password, you should check if your browser saved a password at some point and use it to access your account. It is always advisable to copy and paste the password instead of typing it to avoid errors (though some websites don’t allow this). You can check for saved passwords in the options/preferences section within popular internet browsers: Firefox, Brave, Chrome, and Edge.

Password reset - In case you have trouble accessing your account and you have checked that you are entering the right password (mind the CAPS LOCK and keyboard language), you can try resetting your account password. On most platforms and online services this can be done by clicking on the link named “Forgot your password?” or something similar, which is located on the login page.

Follow the instructions on the “Forgot your password” page and make sure that you have access to the email address/phone number you used to create your account. If you don’t have access to this email or phone, you will need to use the recovery (backup) account if the provider supports that option. Otherwise, you might be left locked out of the account.

Most likely, the service provider will send you a password reset link or code via email or other means of communication, which will enable you to create a new password for your account. From then on, you will use the newly created password to access your account.

Security Questions - Another method to regain access to your account is to provide answers to the security questions, in case you enabled that option in your account security settings. However, some providers are removing this option due to the inefficiency of security questions (they can easily be guessed, etc.). Also, people often don’t change the answers to these questions for years or simply forget them because they don’t have a frequent need for them.

However, if you still have a security question as your account backup solution, make sure the answer is kept in a safe place, that it is not some publicly available information or something easy to guess (“What’s your favourite food?” for example).

Access a trusted device - Having 2-step authentication turned on for all of your accounts is an essential security practice. However, in case the verification method you set up (phone number, app) is not working or has changed, you should try accessing the account from a trusted device. Many service providers offer the option (usually just a checkbox on the 2-step page) to mark a device as trusted so you wouldn’t have to enter 2-step security codes each time you log in on that specific device, such as your home computer.

Make sure that only personal devices (computers, tablets, phones) you use regularly are marked as trusted and never use this feature on public or someone else’s devices.

Request a recovery of a deleted account - In case your account gets deleted, there is a possibility that you could request a recovery, as long as not much time has passed since it was deleted. In case you haven’t used your account for a long time, you probably won’t be able to restore it in full.

The process differs among various service providers. With Google, for instance, a user will be asked a series of questions to confirm it is indeed their account. Advice Google gives to users trying to restore their accounts is to answer as many questions as possible without skipping them entirely, use a familiar device and location, be exact with passwords and security questions, use an email connected to your account which you can access (e.g. a recovery email) and add helpful details if you're asked why you can't access your account.