Troubleshooting login issues on portal.office.com begins with verifying your username and password. If youve forgotten your password, click Cant access your account? to reset it. Ensure your internet connection is stable and try clearing your browsers 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 youre 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.