If you are travelling on the Lake Leake highway between Campbell town and the East Coast, you'll come to a spot in the road clearly marked as the highest point on this road. There are cross roads here. Turn south for a short drive down to Lost Falls (just over 5km). The way is signposted, and obviously the way most traffic has travelled of late. Its only a few minutes walk down to the falls. You walk to the top of the falls. Unfortunately the falls are hard to see, tucked away at the top of deep ravine.
There wasn't a lot of water in the river, but the cascades above the falls would make a nice photo with a bit of rain, and are easily reached by the track from the carpark.
There is a nice view from the top of the falls - not exactly well captured here.