Audi Repair: Audi A4 Cabriolet 2003 Failure to start, diy mechanic, a4 cabriolet

Question
I have an A4 Cabriolet 3.0 Sport Auto.
I drive the car once a week and after using the car for the past 18 weeks with no problems it suddenly failed to start. Just a "whirring" noise. The Engine Management light and ECU light remained lit but the car did not start.
Is this a simple fault to rectify. What must I NOT do to prevent more harm.Can this be sorted by AA or RAC?

Answer
If you hear whirring, it sounds like the starter motor has failed.  A fairly major undertaking for the DIY mechanic since the starter motor is usually a fairly tight fit on the side of the engine block, and has to be exchnaged from underneath.   Just hope that it did not break teeth off the flywheel, because that is a much bigger nightmare...