You may have a chance with the police or sheriff, since you were using a shared space. I would call them, tell them what happened, and ask for their assistance (when you are in town) getting your gear back from them. You live in a society of laws, and law officers are there to help law-abiding citizens deal with lawbreakers. Why not at least ask for help?
No need to speculate that it's gone, just say they won't let you in and you want to pick up your things. If you show up with a uniform and they can't produce your gear, let them explain to the officer what happened to it. At that time you can file a complaint if it's warranted, let the officer guide you. Try to get some kind of report, you may be able to use that in a potential insurance claim.
If there happens to be a strange aroma coming from the practice space when you and the officer arrive, well, karma's a bitch.
I would not just write it off. Someone steals my stuff, I want it or its value back one way or the other. It's easy to lay down and chalk it up to experience, but it's more satisfying to be restored.
Good luck.