abnormal activity / global banned

Hello, my account got global banned few days ago. It was confusing because i din't do anything. I was banned for abnormal activity. Not only that few weeks before that happen, i got notification saying my dll is modified. I am not sure what has happen to my client but clearly i did not install any sort of hacks or tools. I am guessing it is because of my client itself. My client has been installed earlier this year but i have not played that game until June. By that i had to update quite a lot of patches. Hence probably ruined some of the files. I reinstalled my blackshot. All i need right know is just for my account to get unbanned because i clearly did not hack what so ever.