w32tm /resync
w32tm/query /status
https://technet.microsoft.com/en-us/library/cc731191(v=ws.10).aspx
http://www.sysadminlab.net/windows/configuring-ntp-on-windows-server-2012
Start from scratch
If you completely screwed up the config, you can always do the following command and it will completely erase and add a default W32time configuration:
Stop-Service w32time
w32tm /unregister
w32tm /register