trying to restore contacts in yosemite with time machine
To add to what @n1000 said above, some more details:


connect your time machine backup drive
you may need to login as root to get access to that Library folder
choose Finder->Go To folder-> &lt;path-to-library&gt;, where &lt;path-to-libary&gt; is something like "/Volumes/MyTimeMachineDrive/.../Users/keith/Library"
in there you can then browse to Application Support->AddressBook (I forget the details of where exactly it is)
copy the AddressBook back to your MBP and change ownership on it (if you are root) so that it can be read/written to by "keith"
re-login as "keith" and move the AddressBook to same location on your MBP "/Users/keith/Library/Application Support" (I think)
you will be asked to overwrite - go ahead if you want to turf the old AddressBook
open your contacts and voila! all should be well after that...


Please note that I had to do the the above because I had to restore contacts from a time machine backup drive of an old MBP to a new one (and the old MBP was dead, so I could not simply export contacts from it...).