Good day palmetta,
Is it possible that these contacts were being kept in an Internet account such as iCloud?
If you look in System Preferences (under the Apple menu) and select Internet Accounts there may be one or more accounts listed here. If you are using an iCloud account, select it and see if it has the Contacts checkbox checked. If it is not, check that box, go back to the Contacts application (no need to close System Preferences) and see if the contacts you were missing have returned. Note that you need to be connected to the Internet in order for this to work. See this article for information on enabling and disabling iCloud features -
iCloud: Change iCloud feature settings
Other Internet accounts may have features that can be enabled or disabled in the same fashion, so try the other accounts as well as iCloud. See this article for more information on Internet Accounts -
OS X Yosemite: Internet Accounts preferences
Thanks for using Apple Support Communities.
Safe computing,
Brett L