First open the Tropy program, select Open, select desired file.
Opening a Tropy file from outside the program will often not work.
Right click on the project name, select Show Project File...
This is likely due to the original file being moved. Item View accesses the original photo file, so if that file is moved, Tropy will not be able to find it.
To access or locate the original file
Tropy's website offers in-depth help on a wide number of functions within the program.