A file in OneDrive shows 0 KB / "0 bytes" — the document was overwritten with an empty file during sync, or Explorer suddenly lists a document as 0 bytes and it won't open

What's actually wrong

A 0-byte file contains literally no data — there is nothing inside it to repair, and any tool claiming to "fix" a genuinely empty file is lying. The good news: the 0-byte entry is usually a sync artifact (an interrupted upload or a Files On-Demand placeholder that never downloaded), and your real content still exists somewhere — in OneDrive's version history, on the other device that edited the file, or in Office's own auto-save folders. Recovery means finding that other copy, not repairing this one.

Free fixes — try these first

1. Check whether it's just a placeholder. If the file has a cloud icon, it may simply not be downloaded. Right-click it → Always keep on this device, or download it directly from onedrive.com — the web copy is often fine.
2. Version history. On onedrive.com, right-click the file → Version history and restore the last version with a real size. Sync conflicts that overwrite a file with 0 bytes usually leave the previous version intact.
3. Check the machine that last edited the file. Its local OneDrive folder, Word/Excel AutoRecover (File → Info → Manage Document → Recover Unsaved Documents), and %temp% may hold the real content.
4. OneDrive Recycle Bin and full restore. Deleted-then-recreated files land in the onedrive.com Recycle Bin; Microsoft 365 users can also use Settings → Restore your OneDrive to rewind up to 30 days.
5. Windows Previous Versions. Right-click the containing folder → Properties → Previous Versions (works if File History or restore points are on).

If the free fixes fail

Our free diagnosis tells you in seconds whether the file truly contains zero data — in which case we say so plainly, nothing is recoverable from it and your time is better spent on backups — or whether it's actually a partial file whose listed size is wrong, in which case the analyzer shows what survived.