A correct draft is replaced by a shorter, unfinished one and then synchronised. Undo may no longer reach it, but a cloud version history might. Act before making more edits, and do not assume that every file has the same history.
Confirm the file and the account
Open OneDrive through the account that stores the file. Select the file and choose Version history. Microsoft says this feature works with many file types, not only Office documents, but work or school administrators can configure versioning differently.
Check the path, filename and modification time. Two files with the same name in different folders are an easy source of a second mistake.
Inspect before you replace
Use the available preview or download option when possible. Compare a distinctive paragraph, formula or image rather than relying only on the timestamp. If the service permits it, save the candidate as a separate recovery copy first.
In OneDrive’s current process, restoring an older version makes it current, while the previous current version remains in the history. Even so, keep a separate copy when the document is important and the interface allows it. That gives you a simple way to compare both states.
Understand the limits
Version history has a retention window and can be disabled or shortened by organisational settings. It cannot recover a version that never reached the service, and it does not prove that all related files are protected.
After restoration, open the result from the normal folder, verify its content and rename the recovery copy clearly. Then investigate why the overwrite happened. Version history is a useful recovery layer, but synchronisation still propagates mistakes; it is not a substitute for an independent backup.