Do magnetic field lines ever start or end anywhere?

No

Explanation:

The lines of the field of a magnet don't begin or stop at anyplace, they generally make shut circles or loops and will proceed inside magnet (however here and there they are not drawn along these lines). We require an approach to show the bearing of the field.  

The field lines of a magnet don't simply end at the magnetic tip. They go directly through it, so that inside the magnet the magnetic field lines indicates from the south to the north pole.