Well....If the driveshaft fails, and the vertical stabiliser is intact, and you have forward speed (more than 20 kts), you should be able to continue without the tailrotor if you reduce the power. Then you can find a suitable landingspot, set up a steep approach, enter autorotation, cut the fuelflow and make an autorotational emergencylanding.
If you loose tailrotor control on an AS 350, you should reduce power to 60-70 kts, press Hyd Test for 5 sec (or accu-test depending on model), then make a shallow approach with a side-slip to the left, and touch down when the machine gets aligned with the direcion of travel (probably with forward speed). It's easier with the wind coming from the right.
If you loose the vertical stabiliser AND the gearbox, you will probably be well out of CG, plus you don't have the "weather-cock" effect from the tailfin, so the machine will most likely come to a spin nose-down, impossible to recover from.
-AS 350 pilot.