Office application (Word, Excel, Powerpoint, Access) crashed or closed unexpectedly. How can I recover my work?
Resolution:
If autosave is turned on, you can recover files that way. You can also roll back to a previous version of a document. There are steps in Microsoft's documentation page Recover Your Office 365 Files.
If autosave is not turned on, only the last manual save will be available in Recent Files. For the future, turn on autosave to avoid losing work in the future by following the steps in Microsoft's documentation page Help Protect your Files in case of a crash.