Ive been griefed

Since I was gone for a few months since I'm back some of my stuff have disappeared and things in my house has changed, Few things taken from chests, Something different appeared in my floor water, My beds have disappeared, missing diamond armour from chests. What has happened some of my stuff disappeared and what shall I do?

1 part there:Me and Spook have been talking about what has happened he's returned my stuff but we still don't know who is responsible

Well, I can't help much, but it would help the staff and people who can help a lot if you added some stuff like screenshots.

I suggest you look this over and edit your post. It would probably save you quite a bit of time.
https://bigsister.forumotion.com/t50-support-ticket-guidelines

Hello there Akio. a4 made a good point: we are lacking a lot of details. Perhaps some screenshots and such would help?

The other problem is exactly as you stated, you have been gone for a few months. This makes it difficult for us, as we don't have logs to figure out who was on the server at the time, et cetera. However, we will do our best to compensate for what you lost. We'll get back to you with more news!

I have talked with Akio in game about the item loss and he has been compensated.