When you open your project a message tells you it cannot locate a file you used on the timeline and asks you to locate that file.
.TSCPROJ files contain the edit information within your project, but do not actually contain the media within that project (.trec, .mp4, .png, etc.). Instead, the .TSCPROJ file references that media. Therefore, if you move, delete, or rename any of the media and try to open the .TSCPROJ, it will not be able to locate that media associated with the project. It will then give you a chance to locate that media, and your project should open normally. If you would like to learn more about .TSCPROJ and .TSCPROJ files, please look at this article.
It is best practice to avoid renaming, moving, and especially deleting any media that might be associated with a .tscproj. If you need to do so, be sure to take note of where it has been moved so that you will be able to open your project with that media.