This is the Photoshop Elements forum, not the Premiere Elements forum, located here:
https://forums.adobe.com/community/premiere_elements
When you open the project, it should ask you where the first file is located. After you tell it where it is, it should be able to find the rest of them if they are located near the first one. Then save the file. If you move the files again, you will have to relink them again.