You need to BACKUP each project and all of the library files you are currently using. The place names, immages, sources, etc. are not in the xx.pro file, they are stored in common library files separate from the individual data.
If you are moving to a new PC, you may still have the data in the old PC and can retrieve it to a backup. If you reformatted the disk, the data is in the bit bucket and as such is gone.