Aperture stores the location of your Aperture library in its preferences file in your user library in the home folder. If you amde a clean install after the crash (did you?), then Aperture will look for a library in the Pictures folder.
If your Aperture library is somewhere else, you should be able to point Aperture to its location by double clicking the library to open it in Aperture. Then Aperture should automatically upgrade the library to version 3.4.5.
Or launch Aperture with the options ⌥-key held down, to bring up the library chooser panel.
Doesn't this work? If not, where is your library located? How is the drive formatted? Are there any error messages?
The drive crashed completely. Data was extracted at a Mac Servicecompany. The drive was changed to a new one and the extracted data (the aperture library) was inserted on the new HD. The Aperture application was loaded from an Aperture disc by me.
Yes, my Aperture application finds the database for the library,but gives a warning
The library in Users/Pictures/person_name/Aperture Library.aplibrary" cannot be loaded because it is from a newer version of Aperture (That is true because my Aperture version is 3.0 and my library is 3.4.3)
If I update the Application via the AppStore the new application version is 3.4.5 and the error message I get is
"There was an error opening the database for the library "Users/person_name/Pictures/Aperture Library.aplibrary" (because the library version still is 3.4.3)
You can try to repair or rebuild the library by holding down command and option when you launch Aperture.
It's possible that the library is kaput and cannot be repaired. If your drive crashed and you got data recovery, the chances that 100% of the library are sufficiently good to open aren't that great.
This is why you should have a proper backup strategy, and test it. That a simple HD crash put you in this situation is not good. Hard drives crash a lot.