What version of Premiere Elements are you using and on what computer operating system is it running?
I am not clear on your question.
1. Are you saying that you have created several Premiere Elements project files (project.prel), and the Timeline
content of none of these projects has been exported to a movie file from its project. And, when you go to open one of these
saved/closed project files, you are getting "Where is the file.....?" messages?
If this is happening, there are at least 2 possibilities
a. you moved, deleted, or renamed the folders/files that went into the project after the project was saved/closed
b. you have your source files stored on an external hard drive and the external hard drive is malfunctioning, maybe the drive
letter is changing?
2. Or, are you staying that after you export your Timeline to a file saved to the computer hard drive or burned to disc, there
is no video and/or audio in the file OR there is nothing on the disc.
3. Or, something else?
Please be aware...when you import files into a project, all you have in the project are copies of the originals on the computer hard drive.
But, the project's copies need to trace back to those originals at the location where they were when they were first imported into
Please review and consider, and then we can decide how any of the above may relate to your Premiere Elements issues.