Sorry to hear you lost your phone
You can remotely lock or locate the device or wipe it entirely from the Google Play Device Manager (go to Google Play, sign in with the same account that your device is signed into, go to the gear icon on the right, select Device Manager). You can do this even if the phone is not online; location will report whatever was the last place it reported back and a lock/wipe command will be sent out, waiting for the device to come back online to perform it.
However, there's a caveat: This will only work IF you didn't disable the Device Manager from your phone's administrators. Since this is an opt-in service, if you selected NO on the first set up or if you manually disabled remote controls for Device Manager, then this will not work.