If WiFi was turned on, 5 attempts to log im would normally ask for your Google user name and password. If that's not the case you may need to search Google for a way to do a hardware based factory reset.
1. try guessing(what password you usually use)
2. try to input wrong passwords(5 attempts) then input your google account used in the tablet.(like leeshor said)
3. try to factory reset... (i hope you have a good backup)...