Many time you face such a issue that you cannot log in to the admin panel. Or some other user face such issues when try to login.
Please follow following steps to solve this issue
1- Run Command:- php bin/magento admin:user:unlock admin
2- Truncate the admin_user_session table so all session data gets removed
3- In the mage_admin_user table reset failures_num to 0
4- In the mage_admin_user table reset first_failure to NULL for the user
5- Reset Password from DB or from Forgot Password Section of website front end / admin panel
6- Update Password from admin panel by running following query
“UPDATE admin_user SET password = md5(‘YOUR_NEW_SELECTED_PASSWORD’), is_active = 1 WHERE username = ‘admin’;”
YOUR_NEW_SELECTED_PASSWORD will be your new password
Username will be the name of user for which you want to change Password