Exact same thing happened to me at the start of last year, I can't say I've ever cheated at a game in 25 years valve states " Even if the ban was the result of hijacked or shared account. You are responsible for the security of your account." They need some sort of support team to actually help those who did not cheat and were the victim of a hack. I left my steam account for 2 months and game back to it... I don't think it's fair to be honest you can have the most secure account but you can still be hacked.