Install ms office 2013 on windows 8 are head ache. They need different installer based on type of activation. Its between activate thru online or activate by phone. It is a MUST to turn off your wifi or any internet connection when u activate by phone. Dont screw up by forgeting to turn off as u will end up by repair or format your windows. i dont know if this is high security issue that microsoft create so that people cant pirating their software.
If you do screw up like i did (forget to turn wifi), follow this step:-
1) Uninstall the current Office
2) Install again Office with different installer (installer that activate online)
3) uninstall again
4) Now install with the correct installer (activate by phone)
Office somehow stored some id that hardly to find and removed from the laptop. We have to play around install and remove couple times.
Things happen like:-
1) We could not find the option to activate by phone - because wrong installer, solve by get the correct installer
2) option to choose activate by phone has been inactive - because forget to turn off internet/wifi, solve by above solution given