When looking at the front of the camera, make sure the front is facing towards you, and then check to see if the lens barrier slides freely without anything coming in its way.

Make sure there is no debris trapped between the lens barrier and the camera lens. Examine the edges to see if there is anything that is blocking the movement.

Carefully slide the lens barrier back and forth to try to turn the camera back on. To ensure that the camera will turn on, double-check to see that it is properly aligned and on the track