A dream featuring a locker symbolizes things you have kept hidden or to yourself. The objects inside the locker will also have some significance in the dream.
A school locker can symbolize concealed or suppressed feelings or attitudes, or acknowledgement of something in some part of your waking life. While a gym or sports locker can highlight limitations or untapped abilities or potential.
To fail to locate your locker in a dream can suggest that you are feeling insecure, anxious or uncertain about something in some part of your waking life.
If you struggle to get the locker open in the dream then it can suggest that you feel you have lost a part of yourself, or are unsure where you stand in some situation in your waking life.