If the link between the media file and your project file is broken, a panel like this will show up.
![](images/04_refine_effects/link_media.png)
Click on the locate button and find the file. If you reconnect one file, and other files are in the same folder, it should reconnect the remaining files
If you want to explicitly relink media files, right click on the media file in the Project Pane
and then select "link media".