To identify why a user is unable to log in to Salesforce, the administrator should review the login history for the user. The login history shows the date and time of each login attempt, the source IP address, the browser and platform used, the login type (such as username and password or single sign-on), and the status (such as success or failure). The login history can help troubleshoot common login issues such as incorrect username or password, invalid security token, IP restrictions, or login hours violations. Checking the attempted logins by running the setup audit trail, pulling the password history, or resetting the security token for the profile will not help identify why a user is unable to log in. Reference: https://help.salesforce.com/s/articleView?id=sf.monitoring_login_history.htm&type=5