This account has been hacked and someone is playing on it.

I got a notification that said someone had logged into my account from another computer. After that i couldnt log back in. I have had this account for so long and was getting so close to plat. Now this happens. I have the complete history of support tickets that I have filed over time with this account as well as other things. Am I really going to lose my account for this? I cant change my password or anything. I made a ticket with the account but I cant login now to do anything