Troubleshooting login issues on portal.office.com begins with verifying your username and password. If you’ve forgotten your password, click “Can’t access your account?” to reset it. Ensure your internet connection is stable and try clearing your browser’s cache and cookies. Switching to a different browser or device can also help identify browser-specific problems. Check if your organization requires Multi-Factor Authentication (MFA) and ensure you’re using the correct verification method. If issues persist, confirm with your admin that your account is active. Lastly, visit the Microsoft Service Health portal to check for any ongoing outages affecting Office 365 services.