To see a lock in your dream signifies your inability to get what you want. You are being kept out of some activity or situation. Perhaps an aspect of yourself is locked up inside and it needs to be expressed.
To dream that a lock is accidentally shut around your wrist suggests that you are debating on whether to be more open about your feelings or keep them to yourself. You feel that you are taking a major risk in letting your feelings known.
Dreaming about changing locks mean that you are taking matters into your own hand. It also indicates that you are shutting out someone who you were previously close to. To dream that a lock is broken is a metaphor that you are feeling insecure, either emotionally or physically.