To see or use a locker in your dream, signifies aspects of yourself which you have kept hidden inside. Consider what items are inside the locker.
Dreaming of a school locker also denotes hidden feelings that you should recognize in yourself, or knowledge you should learn. Also see “Locker Combination”, below.
[1]1. Secrets and/or hidden aspects of personality.
2. Long hidden or repressed emotions or problems (to see a school locker).
3. A phase of uncertainty, confusion (to be unable to open a locker).
[2]