How to get the Lync client to redownload the address book
Lync 2010
Log off of the Lync client and delete the profile from:
%userprofile%/AppData/Local/Microsoft/Communicator
Then run the following command into an elevated command prompt to add the registry that forces the Lync client to immediately download the address book:
reg add HKLM/Software/Policies/MicrosoftCommunicator /v GalDownloadInitialDelay /t REG_DWORD /d 0 /f
Lync 2013
Log off of the Lync client and delete the profile from:
%userprofile%/appdata/Local/Microsoft/Office/15.0/Lync
Then run the following command into an elevated command prompt to add the registry that forces the Lync client to immediately download the address book:
reg add HKLMSoftwarePoliciesMicrosoftOffice15.0Lync /v GalDownloadInitialDelay /t REG_DWORD /d 0 /f
Note: The Lync address book is saved in the following files on the local workstations: GalContacts.db & GalContacts.db.idx.