No, nothing would get erased, the magnetic forces are very weak, and pole reversals are slow affairs. It won't just flip from one second to the other, instead there is a period where there are no poles or very weak poles (or possibly many poles), that lasts for thousands of years.
The things we know will happen is that:
- Compasses stops working. As the magnetic field weakens we and our electronic toys like GPS's etc need to stop relying on a compass to know the heading. This is not a big problem, most car GPS's already have no compass as the cars magnetism makes them useless anyway, as an example.
Then there are things that may happen:
With a weak or no magnetic field we might get a lot more particles and radiation from the sun. Extinctions have not been correlated with reversals, so they don't seem to be dangerous for life, but this could prove problematic for electronics, meaning we need to shield them better.
Birds that navigate with the help of the magnetic field may become confused. But they navigate with the help of other things as well, so they'll probably just compensate.
That's pretty much it, really.
In any case, it's highly unlikely to happen within the nearest couple of thousand years, so not our problem, really. :-)