If you have a master in Thunder that is no longer on the server or local drive and you want to restore the media on a master you will need to take the following steps.
1. First, re-download the raw media file or files of the masters that need to be replaced.
2. Once the raw media has been downloaded you will next locate the master in Thunder and right click the master and navigate to properties.
3. Once in the properties window of the master select the media tab and highlight the media file right click and navigate to "overwrite media with new file"
4. This will open a 'select new media' window where you will locate your newly downloaded media and select the file to overwrite.
5. Finally Confirm that you do want to overwrite the media.