You need to find a neighbor or friend who understands electricity and has a test meter - it should not take long to discover where the break is.
Very often - when you tightly coil up a cable around something - like on a computer power supply - the tight bend where the cable exits the box stretches the wires inside and with the passage of time they break in two.
If you're an avid "coiler" this may be your problem but a test meter is the best way to find out.
Good luck...
Peccavi
July 2013