I've Been hacked

I've been off of the server for a few months and was about to come back and play with my friends, and one of my friends was asking why i ninjad the guild bank. I looked at my armory and most of my gear was missing. I've spent over $100 on my account and all of my stuff is gone. I have a backup from two months ago, but i wouldnt have my trinket that i bought. Most of our guild bank and gold was ninjad. My friends and i are baffled. The items were taken from the guild bank 15 days ago. I hadn't played since new years.