Thanks for replying. Well, what I did was basically "Saved as.." a new file with the extension type "Backup" that UFTree offers. I first made a backup to the project files, then I did a backup for both project and library files.
When I restored my file (project only) it worked, but the "Places" were all "Missing from library". So I deleted the project and tried to restore the backup file that contained both project and library. When I clicked "Ok" I got the "Bad Local Header" error. I have no clue what that error even is, but I hope someone can help for it is a tedious task to type over 500 places again (even if I remember them).