My current Premiere does not open my old files. How can I solve that? I would like to add to my old work. Please help!
Welcome to the forum.
In some cases, PrPro can Open/Import PREL (Project files from PrE), but PrE has never been able to Open (Importing a Project is not possible in PrE) a PRPROJ file, just as Harm states.
One workaround would be to Export the Timeline from PrPro, and then Import (Get Media/Add Media, depending on version) that output file into PrE for further editing.
Depending on exactly what you are working with, you might want to also consider using a lossless CODEC, like Lagarith, or UT, for those intermediate files.
Also, if you are using Premiere Elements, it has a different forum