Highly unlikely the wire has fallen off. However, if you can see the starter motor (not sure of layout on that engine), try this:
- With the vehicle in neutral or park, have someone hold the key in the start position.
- Assuming the engine is not cranking, rap the starter motor itself with a hammer (via a drift or similar if you cant reach it easily).
- If the starter springs into life, you have identified the problem - worn out brushes in the starter motor itself.