In this situation the crown has often come unstuck and is loose in the mouth, but is still held on the archwire by the bracket. You may need to see both your orthodontist and your general dentist. The orthodontist needs to free the crown from the brace. They may also offer to cement it back in place if they have a suitable cement. This isn't always possible, as orthodontists don't usually fit crowns, so after the orthodontist you will need to go to a general dentist, and then finish the round back at the orthodontist's to have the archwire reconnected to the bracket.
This answer is for general information. Your own case needs an examination by an orthodontist.