It WAS mine at one point. Until someone decided to scam my account a long time ago. By the time I was gullible and I've learned from my mistakes but when I logged in I had a VAC...it's actually why I asked "Why did I get banned?" a while ago in the TF2 discussions.
So, how I understand this:
You had your account hijacked years ago somehow by a form of scam. That person who hijacked your account, used it to cheat in some game (CSGO, TF2) Whichever. But then you logged back into your account to find that you were VAC banned. You never had a problem with that account since?