1. Restart your computer and check if OneDrive is running
2. Make sure that files are completely synced with OneDrive by checking the status in the activity center
3. Check OneDrive's storage and make sure there's enough space for files
4. Check if files are hidden in OneDrive by selecting the 'View' tab and clicking 'Hidden items'
5. Double check if the documents are available from the web version of OneDrive
6. If the files still missing, reinstall OneDrive and try to sync again
7. Finally, contact OneDrive customer service for further assistance