It depends. It could be that the project has indeed been corrupted.
If so, try opening the automatic backup saved in the Adobe Premiere Elements Auto-Save folder.
Welcome to the forum.
There could be lots of reasons that a Project (PREL) file could be corrupted, starting with I/O issues (HDD's going bad, HDD controller going bad, etc.).
Before you do anything else, I would check your AutoSave files. They will be in the AutoSave folder, below your Project's folder. Test those AutoSave PREL files. Note: as the AutoSave files are FIFO (First In - First Out), your AutoSave #3 might be more recent, than #5. Check the Date/Time on those files.
If one, or more, of those Open, I would immediately do a Save_As, or Save_As_a_Copy (similar, but with some differences), and to another HDD on the system, if possible.
If you are getting specifically a damaged project message from the program, you might want to check out the Adobe Tech Note on its recommendations for troubleshooting damaged projects issues. It would be good to follow through its suggestions to rule in or out the interpretation of the problem.