Drag-select not working in Word

Word opens, but drag-selection and the Navigation pane fail, suggesting an add-in, damaged Normal template, or Office installation problem rather than one document. Press Windows+R, run winword /safe, and test a blank document. If selection works in Safe Mode, disable Word and COM add-ins, restart normally, and re-enable them individually. If it still fails, close Word and rename Normal.dotm so Word creates a fresh template; keep the old file. Test another document and confirm headings use Word’s built-in Heading styles, because Navigation does not infer headings from formatting alone. Install Microsoft 365 and Windows updates, then use Settings > Apps > Microsoft 365 > Modify and run Quick Repair, followed by Online Repair if needed. Test a new Windows profile. If every document still fails after Online Repair, capture the Office version and update channel and open Microsoft Support rather than repeatedly reinstalling or deleting registry keys.