Does Aperture crash if you open it on a different library? Try this hold the option key as you start Aperture, this will open the Library create/choose window. Create a new empty library and open it. Does all this work?
If that still crashes create a new user on your machine and log in as that user. Try running Aperture . Does it Open?
Post back the results
Ok Aperture opened on a new library or in a new user account? Makes a big difference in your next steps.
If it was on a new empty library in your account then you need to try a library repair on the original library.
Do this quit Aperture, locate the original library in the Finder now while holding down the option AND command keys double click the library in the Finder. You should get the library repair window run a repair and see if the library will open after that,
BTW what is you're backup situation? Do you have one for this library and how current is it? In cases like this there is always the possibility of loosing part or all of the library.
If the 'it opened' referred to Aperture opening in a new user account post back before doing anything.