The first time we hiked Whitney, we left the portal at 3AM. We made our way through the Mirror Lake-Trail Camp section in the dark. We lost the trail once when we came to an abrupt drop off. We turned around and backtracked to where we knew the trail was. We saw that the trail made a sharp left turn that was out of the beam of our headlamps. Very near Trail Camp in the dawn light we missed a turn again. However, we saw the roof of the now gone solar toilet ahead. We just walked towards it. Four more summits after that first one were completed with no problems.

If you lose the trail, stop and backtrack to where you see the trail again. Look around. You will find the continuation.