If you can't open the app and need to look at your contacts, go to www.icloud.com, sign in, and click on contacts. You can now look at your contacts. To try to fix contacts, see if there is a update for it. if there is, update it. it should work. if it still does not, contact apple at 1-800-MY-APPLE.
Mini Apple Genius
Triple click on the next line to select it all (do not type it)
rm -i L*/Pref*/com.apple.addressbook.plist
copy it to the clipboard, (edit > copy)
press command key and the spacebar and type
and press enter to open the Terminal program
click in there and edit > paste
Now press the enter key
If it asks to confirm and it's the matching com.apple.addressbook.plist file , press Y and enter
If it says anything else, then press N and enter
Quit Terminal and re-open your AddressBook and report.