I apologize that it took so long to respond or look into this. With all the information that I have though it looks as if you didn't have your area claimed and because of that I cannot give it back to you. As far as the creative items go I looked through all of the chests and everything that has an inventory even gaming_robins inventory and there are not any creative items that you have spawned in. The plugin we use that claims your area is called grief prevention and as soon as you place a vanilla chest it claims a small portion of an area for you. I will link a guide to how to claim and use it below.
Claiming so close to someone else claim (whether you really built it or not ) is against the rules. I'm sorry and I know this sucks but claiming your area is one of the first things you must do to ensure that no one else can. Because of the situation I am going to delete your claims next to gaming_robin's and I am not going to punish you for Rule #5 Harassment which would be 1 hour mute/jail. I will link the rules below as well please take a peek at them and since you do have creative access I strongly suggest reading them. With a building wand and some blocks you can rebuild your building some where else that you've claimed and since you have creative it shouldn't take very long. If you'd like help I would love to give you a hand feel free to message me on Discord, the forums, or in game.
~Nikkinz