In order to troubleshoot files that are missing or incomplete after a power outage, consider these steps:

1. Check the connection to your network. If it is not working properly, reboot your router and devices to reconnect.
2. Verify that OneDrive has completed syncing all files. If not, restart the sync and see if that helps.
3. Check whether any of your files are hidden. Show hidden files and folders by going to the View tab in File Explorer.
4. Confirm that all files have downloaded correctly. If you still cannot see them, try downloading them manually.
5. If the issue persists, try resetting OneDrive. To do this, right-click the OneDrive icon in the system tray and click Reset OneDrive.