Does the amp meter move at all when you turn the key switch on? The key switch may be bad, The car will turn over even if the key switch circuit is not closed. But the car will not start because the key circuit is not closed. If the amp meter does not move a little when the key is turned, then check the wires on the back of the key switch and the amp meter, one may be lose and shorted. Otherwise check to see if its firing. Could be a number of things, but if it was running fine, and just quit, it must be electrical. Unless it not getting gas.