Since the existing troubleshooting already covers file repair and Office repair, I’d first try starting Word without add-ins or custom templates:
- Press Windows + R.
- Type
winword /aand press Enter. - Try opening one of the affected documents.
The /a switch starts Word without automatically loading add-ins and global templates, which can help determine whether one of those components is interfering with Word.
If the documents still won’t open, please share more information as suggested by the Independent Advisor that will help narrow down the cause without repeating troubleshooting you’ve already tried.