Why can't I log into my Microsoft Office 365 account?

A knowledge base article about Why can't I log into my Microsoft Office 365 account? provided by the UC Berkeley IT Service Hub - Knowledge Portal

If you’re unable to log into Microsoft Office 365 or related apps, your license may have been deprovisioned due to inactivity, or in some cases due to a change in eligibility.

Check your software eligibility with our Software and Services Eligibility Tool
Activate Microsoft 365 Apps License

For more information visit the Microsoft 365 Apps for Enterprise page.