Hi,
When attempting to open a .spj file for editing, make sure it remains in the same folder as all other project files, including images, audio, and video. If these files are not in the same folder, the program may not be able to read them and open the project.
To resolve the issue, you need to create a folder, and place in this folder the .spj file, image, audio, video files used in the project.
To avoid this issue in the future, save the file using the following steps: Menu > File > Backu up Project File to Folder > Choose the location on your computer where you want to save the file > Click Select Folder.