OneDrive suddenly became empty after university storage policy change Is recovery still possible?

Reducing the quota should not make existing files disappear. Microsoft’s current behavior is to place an over-quota OneDrive into read-only mode: existing content remains downloadable or deletable, while uploads and edits are blocked. An empty My files view therefore suggests a different site, site deletion/replacement, or content deletion rather than ordinary quota enforcement. Ask the SharePoint administrator to record the current personal-site URL and storage usage, compare it with the historical OneDrive URL, and check Active sites and Deleted sites. They should also run the deleted-personal-site query, inspect both recycle-bin stages, Purview retention locations, audit events for file or site deletion, license history, and service health. Do not reprovision the OneDrive or start a new sync, because that can complicate identification. Open a Microsoft 365 support case immediately with the UPN, site URLs, last-known-good date, and UTC discovery time so Microsoft can examine backend restore options before retention windows expire.