How exactly did you save the project? If you just used the normal save project option and then you moved the project file then you file is now correupted and when opeining it you will be ask to pinpoint where the media files used in the project are.
The correct way you should have saved is by going to ¨Menu¨ > ¨FILE¨ > ¨Save Portable Project As¨, this will actually create a folder with the project file and all media that was used in that project. This way you can open the project file again and it will load all the media used because it is in the same folder.
If you did not use the Portable Project option then all you can do now is either start over the project or try and pinpoint where all media is when opening the corrupted project file you have.
You can contact NCH Tech team here: https://www.nch.com.au/support/index.html