Doing anything within Word with a document on flash drive is the most frequently reported cause of document corruption (loss).
I hope you have a backup on your hard drive.
Word does not work with flash drives. Using Word with documents on flash drives is the #1 cause of document corruption. You need to act as if you do not have any flash drives while you are using Word. You can use Windows to copy any document on a flash drive to your hard drive, use Word with it, and when Word is closed, copy it back if you wish.
This means:
- Do not open a document on a flash drive from Word or with Word.
- Do not save a document to a flash drive from within Word.
- Do not print a Word document while it is on a flash drive.