If you cant take items on and off, its not your vendor any more.
If you didn't visit it for over a month, a good chance the owner had to drop the vendors or cancel the contract.
Maybe for legit or no legit reasons.
If your vendor contract was set to no renew, once fallen you would have had like 144 hours to collect your stuff from the vendor sign.
If time past, you are out of luck.
I have a vendor area, and often vendor leave vendors bare for weeks. After about 3 weeks with no contact or message from them, I end their contract.
Ive also given people 30 days warning that I am remodeling my house, to please remove vendors... some never show up.