Could you please tell us where is the Word document saved? Is it OneDrive? Did you use AutoSave function? Besides, does this issue occur with other files?
If there are no previous version records in OneDrive online, the changes that you made in this file were not saved.
For the second issue, I suggest you try following steps to have a check.
- Close all Office apps and OneDrive.
- Go to registry editor and locate to
Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities
, Remove all identities under the "Identities" registry entry. (Here is an article about how to back up and restore the registry in Windows: https://support.microsoft.com/en-us/kb/322756) - Go to Windows Settings > Accounts > Access Work or School, disconnect the existed accounts.
- Then re-open Office apps and OneDrive.
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