1) If you are unable to measure any voltage at the GFCI LINE side, that means you have an open hot conductor or a faulty hot wire splice/termination somewhere upstream (back towards the main electrical panel) from the GFCI receptacle.
2) The problem can be anywhere from the circuit breaker or neutral connection at the panel to any downstream device boxes, junction boxes
or lighting fixture boxes since the circuit can easily tandem thru many of these boxes before reaching it's destination.
3) The breaker needs to be confirmed if 120 volts is present. If the breaker measures OK, then an open conductor is downstream from the panel.
Hope this helps………If you have any additional questions, let me know and I’ll be glad to answer them for you.
Otherwise, don’t forget to rate me before you log Off.
The next time you have an electrical question, you can also request for me at: http://www.justanswer.com/home-improvement/expert-your-electrician ……….Thanks…………..Kevin!