Actually, if the tail-rotor DRIVE fails, you're going down closeby............Have to enter autorotation and cut the engine fuel flow (torque) for an autorotative landing right nearby. If the power (ie torque) is kept on, the heli WILL spin rapidly resulting in disorientation and rapid loss of control. Otherwise an autorotative landing is the ONLY choice in this case (but you've only got seconds to recognise and take action.................) and on landing the heli will try to turn slowly in the SAME direction as the main rotor (gearbox friction) but can be controlled.
However, if the tail rotor is still spinning but CONTROL (ie pitch) is lost, then in many cases you can continue at some speed for a run-on landing (or other manouevre as recommended by the Manufacturer!) onto a smooth surface, as previously mentioned.
Poor guys probably never knew what hit them...............Tail rotor drive failure at low speed/ hover is a killer in no time unfortunately.