Lync Online contacts are lost or missing, or the contact list isn't updated
Scenario 3: Lync Online contacts are lost or missing, or the contact list isn't updated In rare cases, the contact list may be corrupted because of an invalid character in an "out of office" message or because a lingering deprovisioned contact exists. To resolve this problem, force a contact list update to make sure that your information is synchronized. To this, follow these steps: Locate one of the following folders, depending on your operating system: For Lync 2013: Windows 7 and Windows 8: %localappdata%\Microsoft\Office\15.0\Lync\sip_ For Lync 2010: Windows 8, Windows 7, or Windows Vista: %localappdata%\Microsoft\Communicator\sip_ Windows XP: %userprofile%\Local Settings\Application Data \Microsoft\Communicator\sip_ Delete the following files: Galcontacts.db galcontacts.db.idx CoreContact.cache ABS_ .cache Mfugroup.cache PersonalLISDB.cache PresencePhoto.cache Restart Lync, and then wait for 30 minutes for resynchronization to finish.